From: Tao Klerks <tao@klerks.biz>

Fix issues in t3200 branch tests that, if copied, might catch new
contributors out:

Use test_config to show that config state is not being intentionally
left to spill over into other tests.

Use test_cmp_config instead of git config in subshells, so that
git's error code is not lost if/when an unexpected error occurs.

Use output redirection and later content checking instead of
subshells, so that git's error code is not lost if/when an
unexpected error occurs.

Try to eliminate local-fetch-avoiding optimization as it is
error-prone (it is easy to check the wrong thing), hides segfaults,
and yields only a marginal performance improvement anyway.

Introduce local helper test_set_remote to simplify the common local
pattern of setting up a remote via config.

Signed-off-by: Tao Klerks <tao@klerks.biz>

Submitted-As: https://lore.kernel.org/git/pull.1182.git.1647845516517.gitgitgadget@gmail.com