[MERGE] Use a helper function where only one revision is required

[Ian Clatworthy]

Ian Clatworthy has voted approve.
Status is now: Approved


For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C1234138627.4923.8.camel%40sophie.daniel-watkins.co.uk%3E
Project: Bazaar