am 0032ce80: Fix back_up_files() error detection when opening/CRCing the file

Merge commit '0032ce80ac127e6bfb25d727162eee4af208dc77'

* commit '0032ce80ac127e6bfb25d727162eee4af208dc77':
  Fix back_up_files() error detection when opening/CRCing the file