pathspec magic: add '^' as alias for '!'

The choice of '!' for a negative pathspec ends up not only not matching
what we do for revisions, it's also a horrible character for shell
expansion since it needs quoting.

So add '^' as an alternative alias for an excluding pathspec entry.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pathspec.c

@@ -224,6 +224,12 @@ static const char *parse_short_magic(unsigned *magic, const char *elem)
 		char ch = *pos;
 		int i;
 
+		/* Special case alias for '!' */
+		if (ch == '^') {
+			*magic |= PATHSPEC_EXCLUDE;
+			continue;
+		}
+
 		if (!is_pathspec_magic(ch))
 			break;