Make 'read-tree' do a few more of the trivial merge cases.
Make 'read-tree' do a few more of the trivial merge cases.

This cuts down the work for the "real merge" to stuff where
people might actually disagree on the algorithm. The trivial
cases would seem to be totally independent of any policy.

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git