[PATCH] checkpatch.pl: perform commit ID check from external to git folder

[Leon Romanovsky <leon@kernel.org>]

From: Leon Romanovsky <leonro@mellanox.com>

The execution of scripts/checkpatch.pl in folder outside of git produces
complains about invalid commit ID, despite having valid one.

➜  /tmp /home/leonro/src/kernel/scripts/checkpatch.pl \
	--root=/home/leonro/src/kernel \
	--color=always \
	--summary-file /tmp/0001-RDMA-core-Annotate-CMA-unlock-helper-routine.patch

WARNING: Unknown commit id 'e83f195aa45c', maybe rebased or not pulled?
Fixes: e83f195aa45c ("RDMA/cm: Pull duplicated code into cm_queue_work_unlock()")

/tmp/0001-RDMA-core-Annotate-CMA-unlock-helper-routine.patch total: 0 errors, 1 warnings, 7 lines checked

Fixes: a8dd86bf7462 ("checkpatch.pl: warn on invalid commit id")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
---
 scripts/checkpatch.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index eac40f0abd56..286bc78dc6fc 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -966,7 +966,7 @@ sub seed_camelcase_includes {
 sub git_commit_info {
 	my ($commit, $id, $desc) = @_;

-	return ($id, $desc) if ((which("git") eq "") || !(-e ".git"));
+	return ($id, $desc) if ((which("git") eq "") || !(-e "$root/.git"));

 	my $output = `${git_command} log --no-color --format='%H %s' -1 $commit 2>&1`;
 	$output =~ s/^\s*//gm;
--
2.26.2