make happy and rsvndump can be called from within the image as expected:
```
$ make base-buster
...
=> CACHED [stage-1 5/17] COPY --from=rsvndump_image /usr/local/bin/rsvndump /usr/local/bin/rsvndump 0.0s
...
=> => exporting layers 23.3s
=> => writing image sha256:c87640eb4983e93854f1971dbbfdcc11f4ce197dae24ce76a867f2894cb00aa8 0.0s
=> => naming to docker.io/swh-jenkins/base-buster 0.0s
$ docker run -it --rm docker.io/swh-jenkins/base-buster svnrdump --version
svnrdump, version 1.10.4 (r1850624)
compiled Apr 7 2022, 01:09:19 on x86_64-pc-linux-gnu
Copyright (C) 2019 The Apache Software Foundation.
This software consists of contributions made by many people;
see the NOTICE file for more information.
Subversion is open source software, see http://subversion.apache.org/
The following repository access (RA) modules are available:
* ra_svn : Module for accessing a repository using the svn network protocol.
- with Cyrus SASL authentication
- handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
- handles 'file' scheme
* ra_serf : Module for accessing a repository via WebDAV protocol using serf.
- using serf 1.3.9 (compiled with 1.3.9)
- handles 'http' scheme
- handles 'https' scheme
```