undoing a merge

[Adam Mercer]

Hi

I accidentally ran a full merge between two of my branches when I
meant to only cherry pick a single revision i.e. I ran

$ bzr merge ../apps-dev

instead of

$ bzr merge -r 143..144 ../apps-dev

is there a way that I can revert all the changes made by this merge?
I've tried reverting the changes to the individual changed files, but
I still get the following when checking the status:

$ bzr status
pending merges:
  Adam Mercer 2007-06-24 clean up header
    Adam Mercer 2007-06-23 add inspmdc.c
    Adam Mercer 2007-06-23 add xml2mdc.c

how can I cancel this merge and get my tree back to the state it was
before the merge?

Cheers

Adam