Ticket change notification mails should not be translated - take 2.
Ticket change notification mails should not be translated - take 2.

 - also take care of deactivating the translations when preparing the field changes
 - the ticket fields were already translated, replace them temporarily with untranslated ones
 - make sure that for `f['label']`, the `LazyObject.__str__` method won't get called

Closes #8903.


git-svn-id: f68c6b3b1dcd5d00a2560c384475aaef3bc99487@9388 af82e41b-90c4-0310-8c96-b1721e28e2e2

dafrito/trac-mirror,dafrito/trac-mirror,moreati/trac-gitsvn,moreati/trac-gitsvn,exocad/exotrac,moreati/trac-gitsvn,dafrito/trac-mirror,moreati/trac-gitsvn,dafrito/trac-mirror,exocad/exotrac,exocad/exotrac,exocad/exotrac