tapicero: 412 Precondition Failed while creating user db

https://unstable.bitmask.net/cgi-bin/nagios3/extinfo.cgi?type=2&host=urchin.dev.bitmask.i&service=LOG+%2Fvar%2Flog%2Fsyslog

urchin has a lot of those failures:

Feb 24 15:50:19 urchin tapicero[2542]: Creating database user-bdf61a4c6b814d47557ef1f1a66bc2a8 failed due to:
Feb 24 15:50:19 urchin tapicero[2542]: RestClient::PreconditionFailed: 412 Precondition Failed
Feb 24 15:50:24 urchin tapicero[2542]: Prepared storage user-bdf61a4c6b814d47557ef1f1a66bc2a8

azul: this is confusing, is the db actually added or not ? do you know what this "412 Precondition Failed" is ?

(from redmine: created on 2014-02-25, closed on 2014-02-26)