problem upgrading from offlineimap 6.3.4 to 6.6.1

[francois at avalenn.eu]

On Sun, Feb 28, 2016 at 07:29:02PM +0100, Nicolas Sebrecht wrote:
> On Sun, Feb 28, 2016 at 06:00:58PM +0200, Ilias Tsitsimpis wrote:

> > I have created a patch that hopefully will help here[1]. My plan is to
> > include this to the next OfflineIMAP version in Debian, and state at the
> > NEWS file that everyone who is upgrading from v6.3.4 should run
> > 
> >     $ offlineimap --verify-fmd5 || offlineimap --fix-fmd5
> > 
> > before the first use of the newer version.
> > 
> > Could you review this, and/or verify that this is working correctly?
> > 
> > [1] https://github.com/iliastsi/offlineimap/commit/8d07ec308e83665
> 
> From a quick review, this looks fine for a merge. I didn't check the
> validity of the algo, though.
[...] 
> I guess this might be confusing or make bad things (including data loss)
> if applied on mails that has moved from a folder to another one without
> a full filename change because this might lead to UID conflicts.

Indeed at first glance patch seems sound but this potential UID
conflicts annoys me. Is it possible to retrieve the older FMD5 (before
the change of using nametrans) and replace only those matching the old
one ?