[MERGE][BUG #151731] Alternative Cherrypicking merges

[Robert Collins]

Robert Collins has voted tweak.
Status is now: Conditionally approved
Comment:
Looks good to me.

the zz and aa etc variables are not that clearly named. The XXX: comment 
seems like something to either analyse, or to leave the comment out as 
it will show up when someone does analyse merge logic performance.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C47CD5CFF.9050109%40arbash-meinel.com%3E