Description of Problem:
When replying to mail that was previously post-poned, the reply flag on the
original message may not get set.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Start a reply to a message
2. Post-pone it.
3. Switch to another folder.
4. Resume the message and send it.
5. Switch back to original folder.
'r' flag not set on message.
'r' flag set on message, or else a warning saying that it couldn't be set.
Cleaning up bugs on older releases; this is not something we're
probably going to investigate in-house.