[imp] Cannot move messages

[Dan Wilson]

I updated from HEAD a yesterday, and my ability to move messages to a 
different folder has broken and in turn, my filtering.  Here's the message I 
get when running a filter:

******************
 Filter Activity: The message "Re: [horde] Problem, I need Help" from "Jan 
Schneider <jan@horde.org>" has been moved to the folder "INBOX.horde". 
  There was an error moving messages from "" to "horde". This is what the 
server said:  
******************

And when trying to move it manually:

******************
There was an error moving messages from "INBOX" to "horde". This is what the 
server said: 
******************

As you can see, the server doesn't say anything and the logs (with LOG_DEBUG) 
say nothing as well.

Has anyone else seen this behavior?

-Dan