remote: simplify guess_remote_head()

This function had complications which made it hard to extend.

- It used to do two things: find the HEAD ref, and then find a
  matching ref, optionally returning the former via assignment to a
  passed-in pointer. Since finding HEAD is a one-liner, just have a
  caller do it themselves and pass it as an argument.

- It used to manually search through the ref list for
  refs/heads/master; this can be a one-line call to
  find_ref_by_name.

Originally contributed by Jeff King along with the next commit as a
single patch.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-clone.c

@@ -509,8 +509,8 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 
 		mapped_refs = write_remote_refs(refs, &refspec, reflog_msg.buf);
 
-		head_points_at = guess_remote_head(refs, mapped_refs,
-						   &remote_head);
+		remote_head = find_ref_by_name(refs, "HEAD");
+		head_points_at = guess_remote_head(remote_head, mapped_refs);
 	}
 	else {
 		warning("You appear to have cloned an empty repository.");

remote.c

@@ -1452,37 +1452,22 @@ struct ref *get_local_heads(void)
 	return local_refs;
 }
 
-const struct ref *guess_remote_head(const struct ref *refs,
-				    const struct ref *mapped_refs,
-				    const struct ref **remote_head_p)
+const struct ref *guess_remote_head(const struct ref *head,
+				    const struct ref *refs)
 {
-	const struct ref *remote_head = NULL;
-	const struct ref *remote_master = NULL;
 	const struct ref *r;
-	for (r = refs; r; r = r->next)
-		if (!strcmp(r->name, "HEAD"))
-			remote_head = r;
-
-	for (r = mapped_refs; r; r = r->next)
-		if (!strcmp(r->name, "refs/heads/master"))
-			remote_master = r;
 
-	if (remote_head_p)
-		*remote_head_p = remote_head;
-
-	/* If there's no HEAD value at all, never mind. */
-	if (!remote_head)
+	if (!head)
 		return NULL;
 
 	/* If refs/heads/master could be right, it is. */
-	if (remote_master && !hashcmp(remote_master->old_sha1,
-				      remote_head->old_sha1))
-		return remote_master;
+	r = find_ref_by_name(refs, "refs/heads/master");
+	if (r && !hashcmp(r->old_sha1, head->old_sha1))
+		return r;
 
 	/* Look for another ref that points there */
-	for (r = mapped_refs; r; r = r->next)
-		if (r != remote_head &&
-		    !hashcmp(r->old_sha1, remote_head->old_sha1))
+	for (r = refs; r; r = r->next)
+		if (r != head && !hashcmp(r->old_sha1, head->old_sha1))
 			return r;
 
 	/* Nothing is the same */

remote.h

@@ -139,13 +139,12 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs);
 int format_tracking_info(struct branch *branch, struct strbuf *sb);
 
 struct ref *get_local_heads(void);
+
 /*
- * Look in refs for HEAD. Then look for a matching SHA1 in mapped_refs,
- * first checking if refs/heads/master matches. Return NULL if nothing matches
- * or if there is no HEAD in refs. remote_head_p is assigned HEAD if not NULL.
+ * Look for a ref in refs whose SHA1 matches head, first checking if
+ * refs/heads/master matches. Return NULL if nothing matches or if head
+ * is NULL.
  */
-const struct ref *guess_remote_head(const struct ref *refs,
-				    const struct ref *mapped_refs,
-				    const struct ref **remote_head_p);
-
+const struct ref *guess_remote_head(const struct ref *head,
+				    const struct ref *refs);
 #endif