test-lib: bring $remove_trash out of retirement

There's no point in creating a repository or directory only to decide right afterwards that we're skipping all the tests. We can save ourselves the redundant "git init" or "mkdir" and "rm -rf" in this case. We carry around the "$remove_trash" variable because if the directory is unexpectedly gone at test_done time we'll still want to hit the "trash directory already removed" error, but not if we never created the trash directory. See df4c0d1a792 (test-lib: abort when can't remove trash directory, 2017-04-20) for the addition of that error. So let's partially revert 06478dab4c (test-lib: retire $remove_trash variable, 2017-04-23) and move the decision about whether to skip all tests earlier. Let's also fix a bug that was with us since abc5d372ec (Enable parallel tests, 2008-08-08): we would leak $remove_trash from the environment. We don't want this to error out, so let's reset it to the empty string first: remove_trash=t GIT_SKIP_TESTS=t0001 ./t0001-init.sh I tested this with --debug, see 4d0912a206 (test-lib.sh: do not barf under --debug at the end of the test, 2017-04-24) for a bug we don't want to re-introduce. While I'm at it, let's move the HOME assignment to just before test_create_repo, it could be lower, but it seems better to set it before calling anything in test-lib-functions.sh Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>