Teach "git stripspace" the --strip-comments option

With --strip-comments (or short -s), git stripspace now removes lines
beginning with a '#', too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-stripspace.txt

@@ -8,7 +8,7 @@ git-stripspace - Filter out empty lines
 
 SYNOPSIS
 --------
-'git-stripspace' < <stream>
+'git-stripspace' [-s | --strip-comments] < <stream>
 
 DESCRIPTION
 -----------
@@ -16,6 +16,9 @@ Remove multiple empty lines, and empty lines at beginning and end.
 
 OPTIONS
 -------
+-s\|--strip-comments::
+	In addition to empty lines, also strip lines starting with '#'.
+
 <stream>::
 	Byte stream to act on.
 

builtin-stripspace.c

@@ -76,6 +76,11 @@ int cmd_stripspace(int argc, const char **argv, const char *prefix)
 {
 	char *buffer;
 	unsigned long size;
+	int strip_comments = 0;
+
+	if (argc > 1 && (!strcmp(argv[1], "-s") ||
+				!strcmp(argv[1], "--strip-comments")))
+		strip_comments = 1;
 
 	size = 1024;
 	buffer = xmalloc(size);
@@ -84,7 +89,7 @@ int cmd_stripspace(int argc, const char **argv, const char *prefix)
 		die("could not read the input");
 	}
 
-	size = stripspace(buffer, size, 0);
+	size = stripspace(buffer, size, strip_comments);
 	write_or_die(1, buffer, size);
 	if (size)
 		putc('\n', stdout);

t/t0030-stripspace.sh

@@ -392,4 +392,9 @@ test_expect_success \
     git diff expect actual
 '
 
+test_expect_success 'strip comments, too' '
+	test ! -z "$(echo "# comment" | git stripspace)" &&
+	test -z "$(echo "# comment" | git stripspace -s)"
+'
+
 test_done