Rename the recently introduced test-bundle-functions.sh to be
consistent with other lib-*.sh files, which is the convention for
these sorts of shared test library functions.
The new test-bundle-functions.sh was introduced in 9901164d81d (test:
add helper functions for git-bundle, 2021-01-11). It was the only
test-*.sh of this nature.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
