Merge branch 'ho/gitweb-squelch-undef-warning' into maint

Asking gitweb for a nonexistent commit left a warning in the server
log.

Somebody may want to follow this up with a new test, perhaps?
IIRC, we do test that no Perl warnings are given to the server log,
so this should have been caught if our test coverage were good.

* ho/gitweb-squelch-undef-warning:
  gitweb: squelch "uninitialized value" warning

gitweb/gitweb.perl

@@ -7576,7 +7576,7 @@ sub git_object {
 			git_cmd(), 'cat-file', '-t', $object_id) . ' 2> /dev/null'
 			or die_error(404, "Object does not exist");
 		$type = <$fd>;
-		chomp $type;
+		defined $type && chomp $type;
 		close $fd
 			or die_error(404, "Object does not exist");