Added __str__ to exception objects (mostly for debugging failures from the buildbot).
Added __str__ to exception objects (mostly for debugging failures from the buildbot).

babelsberg/babelsberg-r,babelsberg/babelsberg-r,topazproject/topaz,topazproject/topaz,kachick/topaz,babelsberg/babelsberg-r,kachick/topaz,topazproject/topaz,topazproject/topaz,kachick/topaz,babelsberg/babelsberg-r,babelsberg/babelsberg-r