t1300: test "git config --get-all" more thoroughly
t1300: test "git config --get-all" more thoroughly

We check that we can "--get-all" a multi-valued variable,
but we do not actually confirm that the output is sensible.
Doing so reveals that it works fine, but this will help us
ensure we do not have regressions in the next few patches,
which will touch this area.

Signed-off-by: Jeff King <696e3fbcf235d40b6ea1ebd61c87cbea79d444e7@peff.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git