diff --git a/swh/core/pytest_plugin.py b/swh/core/pytest_plugin.py
--- a/swh/core/pytest_plugin.py
+++ b/swh/core/pytest_plugin.py
@@ -11,7 +11,7 @@
 from functools import partial
 from os import path
 from typing import Dict, List, Optional
-from urllib.parse import urlparse
+from urllib.parse import urlparse, unquote
 
 from requests.adapters import BaseAdapter
 from requests.structures import CaseInsensitiveDict
@@ -80,10 +80,11 @@
     logger.debug('get_response_cb(%s, %s)', request, context)
     logger.debug('url: %s', request.url)
     logger.debug('ignore_urls: %s', ignore_urls)
-    if request.url in ignore_urls:
+    unquoted_url = unquote(request.url)
+    if unquoted_url in ignore_urls:
         context.status_code = 404
         return None
-    url = urlparse(request.url)
+    url = urlparse(unquoted_url)
     # http://pypi.org ~> http_pypi.org
     # https://files.pythonhosted.org ~> https_files.pythonhosted.org
     dirname = '%s_%s' % (url.scheme, url.hostname)
diff --git a/swh/core/tests/data/https_forge.s.o/api_diffusion,attachments[uris]=1 b/swh/core/tests/data/https_forge.s.o/api_diffusion,attachments[uris]=1
new file mode 100644
--- /dev/null
+++ b/swh/core/tests/data/https_forge.s.o/api_diffusion,attachments[uris]=1
@@ -0,0 +1 @@
+"something"
diff --git a/swh/core/tests/test_pytest_plugin.py b/swh/core/tests/test_pytest_plugin.py
--- a/swh/core/tests/test_pytest_plugin.py
+++ b/swh/core/tests/test_pytest_plugin.py
@@ -6,10 +6,20 @@
 import requests
 
 from os import path
+from urllib.parse import unquote
 
 from swh.core.pytest_plugin import requests_mock_datadir_factory
 
 
+def test_get_response_cb_with_encoded_url(requests_mock_datadir):
+    # The following urls (quoted, unquoted) will be resolved as the same file
+    encoded_url = 'https://forge.s.o/api/diffusion?attachments%5Buris%5D=1'
+    for url in [encoded_url, unquote(encoded_url)]:
+        response = requests.get(url)
+        assert response.ok
+        assert response.json() == 'something'
+
+
 def test_get_response_cb_with_visits_nominal(requests_mock_datadir_visits):
     response = requests.get('https://example.com/file.json')
     assert response.ok