parse_pathspec: make sure the prefix part is wildcard-free

Prepending prefix to pathspec is a trick to workaround the fact that
commands can be executed in a subdirectory, but all git commands run
at worktree's root. The prefix part should always be treated as
literal string. Make it so.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pathspec.h

@@ -21,7 +21,7 @@ struct pathspec {
 		const char *match;
 		const char *original;
 		unsigned magic;
-		int len;
+		int len, prefix;
 		int nowildcard_len;
 		int flags;
 	} *items;