Fixing via API:
$ lp-shell production devel >>> mp = lp.load('~user/project/branch/+merge/1234567') >>> mp.commit_message = 'my commit message' >>> mp.lp_save() >>> _
Fixing via API:
$ lp-shell production devel '~user/ project/ branch/ +merge/ 1234567' )
>>> mp = lp.load(
>>> mp.commit_message = 'my commit message'
>>> mp.lp_save()
>>> _