```
lang=python
    @pytest.mark.parametrize(
        "value", [pytest.param("foo", id="str"), pytest.param(1, id="int")]
    )
    def test_revision_add_non_bytes_headers(self, swh_storage, value):
        extra_headers = [["foo", b"baz"], ["foo", value]]
        swh_storage.revision_add(
            [{**data.revision, "metadata": {"extra_headers": extra_headers}}]
        )
        (r,) = swh_storage.revision_get([data.revision["id"]])

        assert r["metadata"]["extra_headers"] == extra_headers
```

output:

```
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_api_client.py::TestStorage::test_revision_add_non_bytes_headers[str] PASSED                                                                                                                                  [ 12%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_api_client.py::TestStorage::test_revision_add_non_bytes_headers[int] PASSED                                                                                                                                  [ 25%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_cassandra.py::TestCassandraStorage::test_revision_add_non_bytes_headers[str] FAILED                                                                                                                          [ 37%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_cassandra.py::TestCassandraStorage::test_revision_add_non_bytes_headers[int] FAILED                                                                                                                          [ 50%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_in_memory.py::TestStorage::test_revision_add_non_bytes_headers[str] PASSED                                                                                                                                   [ 62%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_in_memory.py::TestStorage::test_revision_add_non_bytes_headers[int] PASSED                                                                                                                                   [ 75%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py::TestStorage::test_revision_add_non_bytes_headers[str] FAILED                                                                                                                                     [ 87%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py::TestStorage::test_revision_add_non_bytes_headers[int] FAILED                                                                                                                                     [100%]
=================================================================================================================================== FAILURES ===================================================================================================================================
________________________________________________________________________________________________________ TestCassandraStorage.test_revision_add_non_bytes_headers[str] _________________________________________________________________________________________________________

self = <swh.storage.tests.test_cassandra.TestCassandraStorage object at 0x7f1757f0ac50>, swh_storage = <swh.storage.validate.ValidatingProxyStorage object at 0x7f175415d0d0>, value = 'foo'

    @pytest.mark.parametrize(
        "value", [pytest.param("foo", id="str"), pytest.param(1, id="int")]
    )
    def test_revision_add_non_bytes_headers(self, swh_storage, value):
        extra_headers = [["foo", b"baz"], ["foo", value]]
        swh_storage.revision_add(
>           [{**data.revision, "metadata": {"extra_headers": extra_headers}}]
        )

.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py:1145: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
.tox/py3/lib/python3.7/site-packages/swh/storage/validate.py:102: in revision_add
    [dict_converter(Revision, r) for r in revisions]
.tox/py3/lib/python3.7/site-packages/swh/storage/cassandra/storage.py:431: in revision_add
    revobject = revision_to_db(revision)
.tox/py3/lib/python3.7/site-packages/swh/storage/cassandra/converters.py:38: in revision_to_db
    metadata["extra_headers"]
.tox/py3/lib/python3.7/site-packages/swh/storage/converters.py:79: in git_headers_to_db
    ret.append([key, decode_with_escape(values)])
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

value = 'foo'

    def decode_with_escape(value):
        """Decode a bytestring as utf-8, escaping the bytes of invalid utf-8 sequences
        as \\x<hex value>. We also escape NUL bytes as they are invalid in JSON
        strings.
        """
        # escape backslashes
>       value = value.replace(b"\\", b"\\\\")
E       TypeError: replace() argument 1 must be str, not bytes

.tox/py3/lib/python3.7/site-packages/swh/core/utils.py:101: TypeError
------------------------------------------------------------------------------------------------------------------------------ Captured log setup ------------------------------------------------------------------------------------------------------------------------------
WARNING  cassandra.cluster:cql.py:67 Downgrading core protocol version from 66 to 65 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
WARNING  cassandra.cluster:cql.py:67 Downgrading core protocol version from 65 to 4 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 66 to 65 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 65 to 4 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
---------------------------------------------------------------------------------------------------------------------------- Captured log teardown -----------------------------------------------------------------------------------------------------------------------------
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 66 to 65 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 65 to 4 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
________________________________________________________________________________________________________ TestCassandraStorage.test_revision_add_non_bytes_headers[int] _________________________________________________________________________________________________________

self = <swh.storage.tests.test_cassandra.TestCassandraStorage object at 0x7f17547840d0>, swh_storage = <swh.storage.validate.ValidatingProxyStorage object at 0x7f1754ad5150>, value = 1

    @pytest.mark.parametrize(
        "value", [pytest.param("foo", id="str"), pytest.param(1, id="int")]
    )
    def test_revision_add_non_bytes_headers(self, swh_storage, value):
        extra_headers = [["foo", b"baz"], ["foo", value]]
        swh_storage.revision_add(
>           [{**data.revision, "metadata": {"extra_headers": extra_headers}}]
        )

.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py:1145: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
.tox/py3/lib/python3.7/site-packages/swh/storage/validate.py:102: in revision_add
    [dict_converter(Revision, r) for r in revisions]
.tox/py3/lib/python3.7/site-packages/swh/storage/cassandra/storage.py:431: in revision_add
    revobject = revision_to_db(revision)
.tox/py3/lib/python3.7/site-packages/swh/storage/cassandra/converters.py:38: in revision_to_db
    metadata["extra_headers"]
.tox/py3/lib/python3.7/site-packages/swh/storage/converters.py:79: in git_headers_to_db
    ret.append([key, decode_with_escape(values)])
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

value = 1

    def decode_with_escape(value):
        """Decode a bytestring as utf-8, escaping the bytes of invalid utf-8 sequences
        as \\x<hex value>. We also escape NUL bytes as they are invalid in JSON
        strings.
        """
        # escape backslashes
>       value = value.replace(b"\\", b"\\\\")
E       AttributeError: 'int' object has no attribute 'replace'

.tox/py3/lib/python3.7/site-packages/swh/core/utils.py:101: AttributeError
------------------------------------------------------------------------------------------------------------------------------ Captured log setup ------------------------------------------------------------------------------------------------------------------------------
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 66 to 65 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 65 to 4 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
---------------------------------------------------------------------------------------------------------------------------- Captured log teardown -----------------------------------------------------------------------------------------------------------------------------
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 66 to 65 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
WARNING  cassandra.cluster:cql.py:134 Downgrading core protocol version from 65 to 4 for 127.0.0.1:55629. To avoid this, it is best practice to explicitly set Cluster(protocol_version) to the version supported by your cluster. http://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Cluster.protocol_version
_____________________________________________________________________________________________________________ TestStorage.test_revision_add_non_bytes_headers[str] _____________________________________________________________________________________________________________

self = <swh.storage.tests.test_storage.TestStorage object at 0x7f17549d9590>, swh_storage = <swh.storage.validate.ValidatingProxyStorage object at 0x7f175418ec90>, value = 'foo'

    @pytest.mark.parametrize(
        "value", [pytest.param("foo", id="str"), pytest.param(1, id="int")]
    )
    def test_revision_add_non_bytes_headers(self, swh_storage, value):
        extra_headers = [["foo", b"baz"], ["foo", value]]
        swh_storage.revision_add(
>           [{**data.revision, "metadata": {"extra_headers": extra_headers}}]
        )

.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py:1145: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
.tox/py3/lib/python3.7/site-packages/swh/storage/validate.py:102: in revision_add
    [dict_converter(Revision, r) for r in revisions]
.tox/py3/lib/python3.7/site-packages/swh/storage/metrics.py:24: in d
    return f(*a, **kw)
.tox/py3/lib/python3.7/site-packages/swh/storage/metrics.py:77: in d
    r = f(*a, **kw)
.tox/py3/lib/python3.7/site-packages/swh/core/db/common.py:62: in _meth
    return meth(self, *args, db=db, cur=cur, **kwargs)
.tox/py3/lib/python3.7/site-packages/swh/storage/storage.py:564: in revision_add
    revisions_filtered = list(map(converters.revision_to_db, revisions_filtered))
.tox/py3/lib/python3.7/site-packages/swh/storage/converters.py:175: in revision_to_db
    extra_headers = git_headers_to_db(metadata["extra_headers"])
.tox/py3/lib/python3.7/site-packages/swh/storage/converters.py:79: in git_headers_to_db
    ret.append([key, decode_with_escape(values)])
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

value = 'foo'

    def decode_with_escape(value):
        """Decode a bytestring as utf-8, escaping the bytes of invalid utf-8 sequences
        as \\x<hex value>. We also escape NUL bytes as they are invalid in JSON
        strings.
        """
        # escape backslashes
>       value = value.replace(b"\\", b"\\\\")
E       TypeError: replace() argument 1 must be str, not bytes

.tox/py3/lib/python3.7/site-packages/swh/core/utils.py:101: TypeError
_____________________________________________________________________________________________________________ TestStorage.test_revision_add_non_bytes_headers[int] _____________________________________________________________________________________________________________

self = <swh.storage.tests.test_storage.TestStorage object at 0x7f17547732d0>, swh_storage = <swh.storage.validate.ValidatingProxyStorage object at 0x7f17542cd810>, value = 1

    @pytest.mark.parametrize(
        "value", [pytest.param("foo", id="str"), pytest.param(1, id="int")]
    )
    def test_revision_add_non_bytes_headers(self, swh_storage, value):
        extra_headers = [["foo", b"baz"], ["foo", value]]
        swh_storage.revision_add(
>           [{**data.revision, "metadata": {"extra_headers": extra_headers}}]
        )

.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py:1145: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
.tox/py3/lib/python3.7/site-packages/swh/storage/validate.py:102: in revision_add
    [dict_converter(Revision, r) for r in revisions]
.tox/py3/lib/python3.7/site-packages/swh/storage/metrics.py:24: in d
    return f(*a, **kw)
.tox/py3/lib/python3.7/site-packages/swh/storage/metrics.py:77: in d
    r = f(*a, **kw)
.tox/py3/lib/python3.7/site-packages/swh/core/db/common.py:62: in _meth
    return meth(self, *args, db=db, cur=cur, **kwargs)
.tox/py3/lib/python3.7/site-packages/swh/storage/storage.py:564: in revision_add
    revisions_filtered = list(map(converters.revision_to_db, revisions_filtered))
.tox/py3/lib/python3.7/site-packages/swh/storage/converters.py:175: in revision_to_db
    extra_headers = git_headers_to_db(metadata["extra_headers"])
.tox/py3/lib/python3.7/site-packages/swh/storage/converters.py:79: in git_headers_to_db
    ret.append([key, decode_with_escape(values)])
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

value = 1

    def decode_with_escape(value):
        """Decode a bytestring as utf-8, escaping the bytes of invalid utf-8 sequences
        as \\x<hex value>. We also escape NUL bytes as they are invalid in JSON
        strings.
        """
        # escape backslashes
>       value = value.replace(b"\\", b"\\\\")
E       AttributeError: 'int' object has no attribute 'replace'

.tox/py3/lib/python3.7/site-packages/swh/core/utils.py:101: AttributeError

```