Really change patchset column to string

The previous change I26ff56159c2710af1515955d27bf4e9ebfcf76e9 had a
small bug which rendered it basically a noop. Further it missed some 
important parts and test changes.

Change-Id: I6cfb8a6af05e589140c2f7c8b1d7228f6d4d8fcb
3 files changed