tests: use 'test_must_be_empty' instead of 'test_cmp /dev/null <out>'
Using 'test_must_be_empty' is more idiomatic than 'test_cmp /dev/null
out', and its message on error is perhaps a bit more to the point.
This patch was basically created by running:
sed -i -e 's%test_cmp /dev/null%test_must_be_empty%' t[0-9]*.sh
with the exception of the change in 'should not fail in an empty repo'
in 't7401-submodule-summary.sh', where it was 'test_cmp output
/dev/null'.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>