pep8
pep8
Kobo driver: Sideloaded kepubs not added from device properly

When a sideloaded kepub is added from a Kobo device to the calibre
library, it is added as an epub, but the file copied is corrupt.
Fixes #1221035 [Sideloaded kepubs not added to library correctly](https://bugs.launchpad.net/calibre/+bug/1221035)