I have no idea what is causing this to fail, but the mkdtemp pattern used
in other test files seems to fix it.
https://gitlab.com/fdroid/fdroidserver/-/jobs/11776468083
======================================================================
ERROR: test_main (tests.test_signatures.SignaturesTest.test_main)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/builds/fdroid/fdroidserver/tests/test_signatures.py", line 28, in test_main
with TemporaryDirectory() as tmpdir, TmpCwd(tmpdir):
^^^^^^^^^^^^^^
File "/builds/fdroid/fdroidserver/tests/shared_test_code.py", line 44, in __enter__
self.orig_cwd = os.getcwd()
^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory
----------------------------------------------------------------------
This name always confuses me, since there is also test_common.py. And this
module is not actually a test suite, even though it starts with "test".
This also makes for better tab completion, e.g.
python3 -m unittest tests/te[Tab] -> tests/test_
