Created attachment 41298 [details]
remove double entry for errors.py from Makefile.am
Makefile.am tries to isntall twice errors.py, attached patch solves the issue.
Thanks for the fix, I pushed your patch to master.
In future, a "git format-patch" patch would be appreciated even more as it is then easier to retain your details for your contribution.
*** Bug 36962 has been marked as a duplicate of this bug. ***