Cleanup error messages
Cleanup error messages

Make sure error messages include zchunk error message, including when write
callbacks fail

Signed-off-by: Jonathan Dieter <ddc8e8b9809278692339ab749e05e6020a8d4c9a@gmail.com>

rpm-software-management/librepo,Tojaj/librepo,rpm-software-management/librepo,Tojaj/librepo,Tojaj/librepo,rpm-software-management/librepo