lp-propose proposes merge when it should abort

[Thomi Richards]

When using lp-propose, if I exit the editor without specifying a message bzr asks me:

Commit message was not edited, use anyway? ([y]es, [n]o):

If I answer "no", I expect the merge proposal to be aborted (this is the same behavior as 'bzr commit'). Instead, it creates a launchpad merge proposal with an empty description and commit message.