[MERGE] Fix version in dev7 string

[Ian Clatworthy]

Ian Clatworthy has voted tweak.
Status is now: Conditionally approved
Comment:
The fix to the (subtree) compatibility detection is really important - I 
don't think we can upgrade from development6-rr to development7-rr or 2a 
without it. Please add a test as John requested and land this ASAP.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20090605165828.GA4605%40vernstok.nl%3E
Project: Bazaar