[MERGE] revert doesn't preserve contents produced by earlier reverts.

[John Arbash Meinel]

John Arbash Meinel has voted +1.
Status is now: Approved
Comment:
I assume this is basically just using the same 'merge_modified' applied 
to revert (as it is applied to 'merge').

And then checking to see if the target tree differs from the basis tree 
for specific files.

Considering we've done this for merge, it seems correct to me.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C465FB2F0.1050008%40utoronto.ca%3E