I8e1b5b26f03cb75727d2b2e3c9310214a3eac447 introduced a regression that
prevented us from re-cloning a repo that no longer exists on the file
system (e.g. deleted by an operator) but where we still have the cached
`Repo` object.
The problem was that we only updated the remote URL of the repo object
after we wrote it to the Git config. Unfortunately, if the repo no
longer existed on the file system we would attempt to re-clone it with a
possibly outdated remote URL.
`test_set_remote_url` is a regression test for the issue described
above.
`test_set_remote_url_invalid` verifies that the original issue is fixes,
where we updated the remote URL attribute of the repo object, but fail
to update the Git config.
Change-Id: I311842ccc7af38664c28177450ea9e80e1371638