remote rm: handle symbolic refs correctly

In the modern world of reference backends, it is not OK to delete a
symref by unlink()ing the file directly. This must be done via the refs
API.

We do so by adding the symref to the list of references to delete along
with the non-symbolic references, then calling delete_refs() with the
new flags option set to REF_NODEREF.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/remote.c

@@ -539,10 +539,6 @@ static int add_branch_for_removal(const char *refname,
 		return 0;
 	}
 
-	/* make sure that symrefs are deleted */
-	if (flags & REF_ISSYMREF)
-		return unlink(git_path("%s", refname));
-
 	string_list_append(branches->branches, refname);
 
 	return 0;
@@ -788,7 +784,7 @@ static int rm(int argc, const char **argv)
 	strbuf_release(&buf);
 
 	if (!result)
-		result = delete_refs(&branches, 0);
+		result = delete_refs(&branches, REF_NODEREF);
 	string_list_clear(&branches, 0);
 
 	if (skipped.nr) {