Have a constant extern refspec for "--tags"

The refspec refs/tags/*:refs/tags/* is sufficiently common and generic
to merit having a constant instead of generating it as needed.

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fetch.c

@@ -127,14 +127,8 @@ static struct ref *get_ref_map(struct transport *transport,
 		/* Merge everything on the command line, but not --tags */
 		for (rm = ref_map; rm; rm = rm->next)
 			rm->merge = 1;
-		if (tags == TAGS_SET) {
-			struct refspec refspec;
-			refspec.src = "refs/tags/";
-			refspec.dst = "refs/tags/";
-			refspec.pattern = 1;
-			refspec.force = 0;
-			get_fetch_map(remote_refs, &refspec, &tail, 0);
-		}
+		if (tags == TAGS_SET)
+			get_fetch_map(remote_refs, tag_refspec, &tail, 0);
 	} else {
 		/* Use the defaults */
 		struct remote *remote = transport->remote;

remote.c

@@ -2,6 +2,15 @@
 #include "remote.h"
 #include "refs.h"
 
+static struct refspec s_tag_refspec = {
+	0,
+	1,
+	"refs/tags/",
+	"refs/tags/"
+};
+
+const struct refspec *tag_refspec = &s_tag_refspec;
+
 struct counted_string {
 	size_t len;
 	const char *s;

remote.h

@@ -51,6 +51,8 @@ struct refspec {
 	char *dst;
 };
 
+extern const struct refspec *tag_refspec;
+
 struct ref *alloc_ref(unsigned namelen);
 
 struct ref *copy_ref_list(const struct ref *ref);