Re: [PATCH v5 20/20] rebase: rename the two primary rebase backends

Jonathan Nieder [off-list ref] writes:

Sorry for the lack of clarity.  I mean allowing

	[rebase]
		backend = am
		backend = apply
		backend = futuristic

with behavior

- on "git" that understands am but not apply or futuristic, use the am
  backend
- on "git" that understands apply but not am or futuristic, use the
  apply backend
- on "git" that understands apply and futuristic, use the futuristic
  backend

That way, a single config file is usable on all three versions of Git.

IOW, make rebase.backend a multi-valued one and use it when one and
only one value is a recognised one?  What would an error message say
when none is recognised, and when would that be issued?

I like the general direction it takes, but I think it would be
simpler to (1) die when we see what we do not recognise and (2)
teach the latest one that "am" is a synonym for "apply", without
even advertising "am".