Remove leading newline characters from tag messages

Fixes a regression introduced in commit 936295c (Simplify commit and tag
parsing, 2015-03-03).

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

parsing.c

@@ -216,6 +216,9 @@ struct taginfo *cgit_parse_tag(struct tag *tag)
 		}
 	}
 
+	while (p && *p == '\n')
+		p++;
+
 	if (p && *p)
 		ret->msg = xstrdup(p);