D19080: [WIP] Make file overwrite a bit safer

[Chinmoy Ranjan Pradhan]

chinmoyr added a dependent revision: D18904: [FileCopyJob] Clean up after file 
copy operation is cancelled.

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D19080

To: chinmoyr, dfaure, ngraham
Cc: kde-frameworks-devel, michaelh, ngraham, bruns