[MERGE][Bug #198417] 'ancestor:' revspec defaults to the parent branch

[Ian Clatworthy]

Ian Clatworthy has voted approve.
Status is now: Approved
Comment:
I'll merge.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C1234095218.5035.5.camel%40sophie.daniel-watkins.co.uk%3E
Project: Bazaar