Fix #1388481 [Little typo](https://bugs.launchpad.net/calibre/+bug/1388481)
Fix #1388479 [Little typo](https://bugs.launchpad.net/calibre/+bug/1388479)
Fix #1388462 [Little typo?](https://bugs.launchpad.net/calibre/+bug/1388462)
Fix #1388459 [Little typo? (semantics)](https://bugs.launchpad.net/calibre/+bug/1388459)