version 6.5.3: ['[ALREADYEXISTS] Duplicate folder name (Failure)

[ael]

As noted in the previous message, all the problem folders were empty.
Perhaps this corner case is not handled properly in one of the code
paths.

I have now manually deleted the matching empty directories on the
Maildir, and this seems to have cured the problem on this machine. 
I *thought* that I had already tried that, but maybe not.

ael