Implementing git-am -3 with git-apply -3?

Hi Junio,

I noticed that you implemented a 3-way merge fallback[1] in git-apply
that is meant to be similar to git-am's.

I wonder if it is possible to implement the 3-way merge in git-am
using git-apply. Are there any issues/deficiencies that I need to be
aware of?

So far, I noticed that:

* git-apply does not handle renames in the index.

* It could probably try harder at merging submodules (perhaps by using
merge_submodule()?)

[1] http://thread.gmane.org/gmane.comp.version-control.git/201238

Thanks,
Paul