cli: require argument for `jj open`
The current checkout is always open, so it doesn't make sense to have
that as default.
@@ -814,7 +814,7 @@ fn get_app<'a, 'b>() -> App<'a, 'b> {
.arg(message_arg());
let open_command = SubCommand::with_name("open")
.about("Mark a commit open, making new work be added to it")
- .arg(Arg::with_name("revision").index(1).default_value("@"));
+ .arg(Arg::with_name("revision").index(1).required(true));
let duplicate_command = SubCommand::with_name("duplicate")
.about("Create a copy of the commit with a new change id")
.arg(Arg::with_name("revision").index(1).default_value("@"));
