D18900: Avoid side effects due to stale errno value

[Alexander Stippich]

astippich accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R286 KFileMetaData

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D18900

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