The "merge none" (don't automerge) flag was only to aide in
merge trivial tests. We can easily determine whether merge
trivial resulted in a trivial merge or an automerge by examining
the REUC after automerge has completed.
The default merge_file level was XDL_MERGE_MINIMAL, which will
produce conflicts where there should not be in the case where
both sides were changed identically. Change the defaults to be
more aggressive (XDL_MERGE_ZEALOUS) which will more aggressively
compress non-conflicts. This matches git.git's defaults.
Increase testing around reverting a previously reverted commit to
illustrate this problem.
Any well-behaved program should write a descriptive message to the
reflog whenever it updates a reference. Let's make this more prominent
by removing the version without the reflog parameters.
