Hi,

Whilst working on the Reproducible Builds effort [0], we noticed that
whipper could not be built reproducibly.

This was because it ships a different binary package depending
on whether the tests are run or not. Specifically, the testsuite
did not clean up a "test/cover.jpg" file, which was then installed
into the .deb.

Patch attached.

 [0] https://reproducible-builds.org/


Regards,