regression: calendar dropdown did not roll over to October

My colleague and I regularly use the month-view calendar dropdown to check times in particular time zones and to help work out numerical dates such as "two Mondays prior to 25 Sept" and so on. This morning we had a baffling conversation because he mentioned that 7 October was a Saturday.

Looking at my calendar, I saw that he was correct, but then I realized that it was showing me September (and yes, 7 Sept was a Saturday). Skipping forward to October got me the right data.

This reminds me suspiciously of bug #649800 which I filed against the Maverick beta back in 2010, and I suspect this is a regression.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: indicator-datetime 13.10.0+13.10.20130930-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-9.16-generic 3.11.2
Uname: Linux 3.11.0-9-generic x86_64
ApportVersion: 2.12.5-0ubuntu1
Architecture: amd64
Date: Thu Oct 3 08:23:30 2013
EcryptfsInUse: Yes
MarkForUpload: True
SourcePackage: indicator-datetime
UpgradeStatus: Upgraded to saucy on 2013-09-17 (15 days ago)