On the one hand, there do exist systems that have type and don't have command.

On the other hand, none of those systems are in use in our test lab, whereas
there are systems in our test lab that implement type idiosyncratically.
Furthermore, in the event that anyone needs to run ATF unit tests on a system
that's too old to have command, workarounds probably exist such as
SHELL=/bin/bash.

I suggest rather than spending further developer time on this, let's
just merge it. We can tidy it up later if it turns out to be necessary.