Flags are provided with a default mimetype of emails,
and we want to avoid creating email items if a flag of a
groupware item changed.
notes from randa:
- Fix assert in ItemCreateJob, to allow no mimetype in case of merge and
-> you are talking about kdepimlibs/akonadi/job/itemcreatejob ? -> I see there no assert.
- Allow merging for everything except for payloads
-> I do not understand