support path parameter

Author: liyi3c

git-diff-blame

@@ -27,10 +27,15 @@ $git_root =~ s/^\s+//;
 $git_root =~ s/\s+$//;
 chdir($git_root) or die "$!";
 
-my ($oldrev, $newrev) = @ARGV;
+my ($oldrev, $newrev, $paths) = @ARGV;
 $oldrev ||= 'HEAD';
 if ($newrev) {
-	open($diff, '-|', 'git', '--no-pager', 'diff', $oldrev, $newrev) or die;
+	if ($paths) {
+		open($diff, '-|', 'git', '--no-pager', 'diff', $oldrev, $newrev, $paths) or die;
+	} else {
+		open($diff, '-|', 'git', '--no-pager', 'diff', $oldrev, $newrev) or die;
+	}
+	
 } else {
 	open($diff, '-|', 'git', '--no-pager', 'diff', $oldrev) or die;
 }