sync with gmail: cannot create folder, already exists (not using nametrans, using readonly on gmail repository)

[Peter Schüller]

I am using offlineimap with Gmail. I used it for a long while. Recently I upgraded to ubuntu 14.04.

Now syncing does not work anymore:

Creating folder ML[peter-gmail-at-gmail]
ERROR: Creating folder ML on repository peter-gmail-at-gmail
  Folder 'ML'[peter-gmail-at-gmail] could not be created. Server responded: ('NO', ['[ALREADYEXISTS] Duplicate folder name (Failure)'])
ERROR: Folder 'ML'[peter-gmail-at-gmail] could not be created. Server responded: ('NO', ['[ALREADYEXISTS] Duplicate folder name (Failure)'])

I am using fsync=False
I am not using nametrans for any of these repositories.
I am using type=Gmail and readonly=true for the Gmail
My local repository has type=Maildir

Gmail as well as the local repository have a folder 'ML'

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: offlineimap 6.5.4-2
ProcVersionSignature: Ubuntu 3.13.0-30.54-generic 3.13.11.2
Uname: Linux 3.13.0-30-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Jun 28 17:46:56 2014
InstallationDate: Installed on 2012-06-26 (732 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
SourcePackage: offlineimap
UpgradeStatus: Upgraded to trusty on 2014-06-28 (0 days ago)