[PATCH 1/1 v2] checkpatch: remove false warning for commit reference

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

Checkpatch warns of an incorrect commit reference style
for any hexadecimal number of 12 digits and more.

Numbers of 12 digits are not necessarily commit ids.

For an example provoking the problem see
https://patchwork.kernel.org/patch/9170897/

Checkpatch should only warn if the number refers to an
existing commit.

Cc: Joe Perches <joe@perches.com>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
v2:
	changed formatting according to suggestions by Joe Perches
---
 scripts/checkpatch.pl | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4b9569fa931b..3895978c5bbd 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -866,6 +866,7 @@ sub git_commit_info {
 #		    echo "commit $(cut -c 1-12,41-)"
 #		done
 	} elsif ($lines[0] =~ /^fatal: ambiguous argument '$commit': unknown revision or path not in the working tree\./) {
+		$id = undef;
 	} else {
 		$id = substr($lines[0], 0, 12);
 		$desc = substr($lines[0], 41);
@@ -2605,7 +2606,8 @@ sub process {
 			($id, $description) = git_commit_info($orig_commit,
 							      $id, $orig_desc);
 
-			if ($short || $long || $space || $case || ($orig_desc ne $description) || !$hasparens) {
+			if (defined($id) &&
+			   ($short || $long || $space || $case || ($orig_desc ne $description) || !$hasparens)) {
 				ERROR("GIT_COMMIT_ID",
 				      "Please use git commit description style 'commit <12+ chars of sha1> (\"<title line>\")' - ie: '${init_char}ommit $id (\"$description\")'\n" . $herecurr);
 			}
-- 
2.11.0