Leaks memory when running with autorefresh over long periods of time

[Clint Byrum]

After running for about 100 hours, offlineimap was using 800MB of RAM. I have one IMAP account, and my rules are very basic (skipping a few folders).

[general]
accounts = SpamapS
maxsyncaccounts = 2
maxconnections = 2
ui = Blinkenlights
autorefresh = 1

[Account SpamapS]
localrepository = Local
remoterepository = Remote
autorefresh = 2

[Repository Local]
type = Maildir
localfolders = ~/Mail/SpamapS
folderfilter = lambda folder: folder not in ['save', 'oldin']

[Repository Remote]
type = IMAP
remotehost = xxx.xxx.com
remoteuser = xxxxxxxxx
ssl = yes
remotepass = xxxxxxxxxxxxx
folderfilter = lambda folder: folder not in ['Sent','sru']
cert_fingerprint = 4b10f1a45ac47494e7a310b653c480df46c24e1a

offlineimap was actuall invoked using "offlineimap -u TTYUI"

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: offlineimap 6.5.4-2
ProcVersionSignature: Ubuntu 3.8.0-23.34-generic 3.8.11
Uname: Linux 3.8.0-23-generic x86_64
NonfreeKernelModules: nvidia wl
ApportVersion: 2.9.2-0ubuntu8.1
Architecture: amd64
Date: Sun Jul 7 08:24:15 2013
InstallationDate: Installed on 2010-10-22 (988 days ago)
InstallationMedia: Xubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101008.1)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: offlineimap
UpgradeStatus: Upgraded to raring on 2013-02-08 (148 days ago)