checkout: retire --ignore-other-worktrees in favor of --force

As a safeguard, checking out a branch already checked out by a different
worktree is disallowed. This behavior can be overridden with
--ignore-other-worktrees, however, this option is neither obvious nor
particularly discoverable. As a common safeguard override, --force is
more likely to come to mind. Therefore, overload it to also suppress the
check for a branch already checked out elsewhere.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-checkout.txt

@@ -111,6 +111,9 @@ OPTIONS
 +
 When checking out paths from the index, do not fail upon unmerged
 entries; instead, unmerged entries are ignored.
++
+By default, checking out a branch already checked out in another worktree
+is disallowed. This overrides that safeguard.
 
 --ours::
 --theirs::
@@ -225,12 +228,6 @@ This means that you can use `git checkout -p` to selectively discard
 edits from your current working tree. See the ``Interactive Mode''
 section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
 
---ignore-other-worktrees::
-	`git checkout` refuses when the wanted ref is already checked
-	out by another worktree. This option makes it check the ref
-	out anyway. In other words, the ref can be held by more than one
-	worktree.
-
 <branch>::
 	Branch to checkout; if it refers to a branch (i.e., a name that,
 	when prepended with "refs/heads/", is a valid ref), then that

builtin/checkout.c

@@ -35,7 +35,6 @@ struct checkout_opts {
 	int writeout_stage;
 	int overwrite_ignore;
 	int ignore_skipworktree;
-	int ignore_other_worktrees;
 
 	const char *new_branch;
 	const char *new_branch_force;
@@ -903,7 +902,8 @@ static void check_linked_checkout(struct branch_info *new, const char *id)
 		strbuf_rtrim(&gitdir);
 	} else
 		strbuf_addstr(&gitdir, get_git_common_dir());
-	die(_("'%s' is already checked out at '%s'"), new->name, gitdir.buf);
+	die(_("'%s' is already checked out at '%s'; use --force to override"),
+	    new->name, gitdir.buf);
 done:
 	strbuf_release(&path);
 	strbuf_release(&sb);
@@ -1151,7 +1151,7 @@ static int checkout_branch(struct checkout_opts *opts,
 		char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
 		if (head_ref &&
 		    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)) &&
-		    !opts->ignore_other_worktrees)
+		    !opts->force)
 			check_linked_checkouts(new);
 		free(head_ref);
 	}
@@ -1198,8 +1198,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 			 N_("do not limit pathspecs to sparse entries only")),
 		OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
 				N_("second guess 'git checkout no-such-branch'")),
-		OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
-			 N_("do not check if another worktree is holding the given ref")),
 		OPT_END(),
 	};
 

builtin/worktree.c

@@ -303,7 +303,7 @@ static int add(int ac, const char **av, const char *prefix)
 
 	argv_array_push(&cmd, "checkout");
 	if (force)
-		argv_array_push(&cmd, "--ignore-other-worktrees");
+		argv_array_push(&cmd, "--force");
 	if (new_branch)
 		argv_array_pushl(&cmd, "-b", new_branch, NULL);
 	if (new_branch_force)