parse_color: fix return value for numeric color values 0-8

When commit 695d95d refactored the color parsing, it missed
a "return 0" when parsing literal numbers 0-8 (which
represent basic ANSI colors), leading us to report these
colors as an error.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

color.c

@@ -112,6 +112,7 @@ static int parse_color(struct color *out, const char *name, int len)
 		} else if (val < 8) {
 			out->type = COLOR_ANSI;
 			out->value = val;
+			return 0;
 		} else if (val < 256) {
 			out->type = COLOR_256;
 			out->value = val;