[Dockerfile.test] explicitly COPY .git/

[jpopelka]

Tests in user-cont#237 are failing because CI can't build the test image (from Dockerfile.test).

10:48:09  Step 13/15 : RUN cd /tmp/tmp/ && pip3 install . && rm -rf /tmp/tmp/
...
10:48:13        File "/tmp/pip-req-build-b3d672cb/.eggs/setuptools_scm-3.3.3-py3.7.egg/setuptools_scm/__init__.py", line 113, in _do_parse
10:48:13          "use git+https://github.com/user/proj.git#egg=proj" % config.absolute_root
10:48:13      LookupError: setuptools-scm was unable to detect version for '/tmp/pip-req-build-b3d672cb'.
10:48:13      
10:48:13      Make sure you're either building from a fully intact git repository or PyPI tarballs. Most other sources (such as GitHub's tarballs, a git checkout without the .git folder) don't contain the necessary metadata and will not work.

It seems that there's no .git/ folder.
make image-test works on my machine and I don't see any problem in Dockerfile.test.
But let's try to explicitly copy the .git/

[jpopelka]

damn, the CI is not run at all here, so I guess you'd have to merge this first to see how it goes :-D

[jpopelka]

Now I remember we saw this in packit-service too. The Jenkinsfile change should fix it.