Re: [PATCH v2] fetch: Protect branches checked out in all worktrees

But all of that means we could actually drop check_not_current_branch()
in favor of the update_local_ref() check. Doing this:

diff --git a/builtin/fetch.c b/builtin/fetch.c
index f7abbc31ff..c52c44684a 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c

@@ -869,7 +869,7 @@ static int update_local_ref(struct ref *ref,
 	}
 
 	if (current_branch &&
-	    !strcmp(ref->name, current_branch->name) &&
+	    !strcmp(ref->name, current_branch->refname) &&
 	    !(update_head_ok || is_bare_repository()) &&
 	    !is_null_oid(&ref->old_oid)) {
 		/*

@@ -1385,20 +1385,6 @@ static int prune_refs(struct refspec *rs, struct ref *ref_map,
 	return result;
 }
 
-static void check_not_current_branch(struct ref *ref_map)
-{
-	struct branch *current_branch = branch_get(NULL);
-
-	if (is_bare_repository() || !current_branch)
-		return;
-
-	for (; ref_map; ref_map = ref_map->next)
-		if (ref_map->peer_ref && !strcmp(current_branch->refname,
-					ref_map->peer_ref->name))
-			die(_("Refusing to fetch into current branch %s "
-			    "of non-bare repository"), current_branch->refname);
-}
-
 static int truncate_fetch_head(void)
 {
 	const char *filename = git_path_fetch_head(the_repository);

@@ -1587,8 +1573,6 @@ static int do_fetch(struct transport *transport,
 
 	ref_map = get_ref_map(transport->remote, remote_refs, rs,
 			      tags, &autotags);
-	if (!update_head_ok)
-		check_not_current_branch(ref_map);
 
 	if (tags == TAGS_DEFAULT && autotags)
 		transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");

passes the entire test suite except for one test which expects:

  git fetch . side:main

to fail. But that is only because "side" and "main" point to the same
commit, and thus the fetch is a noop. The code in update_local_ref()
covers that case before checking the HEAD case (which I would argue is
a completely reasonable outcome).