D17000: Make sure there is only one MTime per document in the MTimeDB

[Stefan Brüns]

bruns removed a dependency: D17001: Add unittest for document replacement.

REPOSITORY
  R293 Baloo

REVISION DETAIL
  https://phabricator.kde.org/D17000

To: bruns, #baloo, #frameworks, poboiko, ngraham
Cc: kde-frameworks-devel, ashaposhnikov, michaelh, astippich, spoorun, ngraham, 
bruns, abrahams