Add tests for the git scripts
If we have time, we might want to add tests and CI for the git scripts. Here are the ones I used to test #29603 (moved):
$ TOR_FULL_GIT_PATH=/tmp/test-origin git-setup-dirs.sh
$ TOR_FULL_GIT_PATH=/tmp/test-upstream TOR_UPSTREAM_REMOTE_NAME=upstream git-setup-dirs.sh
$ TOR_FULL_GIT_PATH=/tmp/test-wkt TOR_WKT_NAME=. TOR_MASTER_NAME=master git-setup-dirs.sh
We might also want to test them with -n, -u, git-pull-all.sh, and git-merge-forward.sh.