ERROR: These branches have diverged.

[Nicholas Allen]

I'm not really sure I understand your problem. I don't get why you 
revert after every merge. The merge gives you the latest changes which 
is what you want right? Once you have merged you then have the 
opportunity to resolve conflicts (if there were any) and to decide if 
you still want the changes you merged in. If you do then you should 
commit after you have merged to indicate you are happy with how bzr 
merged the 2 branches.

So it looks to me like you want to run the commit command after merging 
(assuming you are happy with the merge that is...)

Nick