Merge branch 'test-updates-and-related-bug-fixes' into 'master'

Test updates and related bug fixes

I just set up some big tests of generating repos based on feeding as many random APKs into `fdroid update` as possible.  On our jenkins server, the tests copy all of the APKs that the jenkins server has generated and builds a repo from them.  This process caught lots of little glitches in the whole process.  While these little glitches are usually caused by problematic APKs, `fdroid update` should handle them gracefully.  Hopefully this set of fixes accomplishes that.

diff --cc fdroidserver/common.py
Simple merge