[PATCH v3 1/4] git-submodule: remove unused is_zero_oid() function

The is_zero_oid() function in git-submodule.sh has not been used since
e83e3333b57 (submodule: port submodule subcommand 'summary' from shell
to C, 2020-08-13), so we can remove it.

This was the last user of the sane_egrep() function in
git-sh-setup.sh. I'm not removing it in case some out-of-tree user
relied on it. Per the discussion that can be found upthread of [1].

1. https://lore.kernel.org/git/87tuiwjfvi.fsf@evledraar.gmail.com/ (local)

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 git-submodule.sh | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/git-submodule.sh b/git-submodule.sh
index dbd2ec20503..aeb96c58243 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh

@@ -63,11 +63,6 @@ isnumber()
 	n=$(($1 + 0)) 2>/dev/null && test "$n" = "$1"
 }
 
-# Given a full hex object ID, is this the zero OID?
-is_zero_oid () {
-	echo "$1" | sane_egrep '^0+$' >/dev/null 2>&1
-}
-
 # Sanitize the local git environment for use within a submodule. We
 # can't simply use clear_local_git_env since we want to preserve some
 # of the settings from GIT_CONFIG_PARAMETERS.

-- 
2.33.0.984.gea2c3555113