Merge branch 'dk/worktree-dup-checkout-with-bare-is-ok'

In a worktree connected to a repository elsewhere, created via "git
worktree", "git checkout" attempts to protect users from confusion
by refusing to check out a branch that is already checked out in
another worktree.  However, this also prevented checking out a
branch, which is designated as the primary branch of a bare
reopsitory, in a worktree that is connected to the bare
repository.  The check has been corrected to allow it.

* dk/worktree-dup-checkout-with-bare-is-ok:
  worktree: allow the main brach of a bare repository to be checked out

t/t2025-worktree-add.sh

@@ -138,6 +138,14 @@ test_expect_success 'checkout from a bare repo without "add"' '
 	)
 '
 
+test_expect_success '"add" default branch of a bare repo' '
+	(
+		git clone --bare . bare2 &&
+		cd bare2 &&
+		git worktree add ../there3 master
+	)
+'
+
 test_expect_success 'checkout with grafts' '
 	test_when_finished rm .git/info/grafts &&
 	test_commit abc &&

worktree.c

@@ -345,6 +345,8 @@ const struct worktree *find_shared_symref(const char *symref,
 
 	for (i = 0; worktrees[i]; i++) {
 		struct worktree *wt = worktrees[i];
+		if (wt->is_bare)
+			continue;
 
 		if (wt->is_detached && !strcmp(symref, "HEAD")) {
 			if (is_worktree_being_rebased(wt, target)) {