[v2] cmd: Command chain fixes

[Flávio J. Saraiva]

I'd like to cancel/recall this patch, which is a partial fix.

I have detected many issues that can't be properly fixed until the
parsing stage is redone, such as this one, so it's better to only
tackle them after redoing the parsing stage.

I wanted to keep the tests, but didn't understand how to properly add
them as TODOs. (if it's even possible)