[Dovecot] Bug: maidirsize double counting moved messages

[Bill Boebel]

The maildirsize file is double counting messages when moving them from
folder to folder when "maildir_copy_with_hardlinks = no":

1024000000000S
99337571 19370
14010590 2       <--- moved from subfolder to subfolder
-7005295 -1
14010590 2       <--- moved from subfolder to INBOX
-7005295 -1
14010590 2       <--- moved from INBOX to subfolder
-7005295 -1
14010590 2       <--- moved from subfolder to subfolder
-7005295 -1

When I change "maildir_copy_with_hardlinks" to "yes", this problem only
occurs when moving in and out of the INBOX, but not when moving from
subfolder to subfolder:

7005295 1        <--- moved from subfolder to subfolder
-7005295 -1
14010590 2       <--- moved from subfolder to INBOX
-7005295 -1
14010590 2       <--- moved from INBOX to subfolder
-7005295 -1
7005295 1        <--- moved from subfolder to subfolder
-7005295 -1