[setup] Synchronize pypi package 1.2 with 2.1
[setup] Synchronize pypi package 1.2 with 2.1

Parser for requirements are different in Python 2 and Python 3.
Enforce the same result in these 3 conditions.

Change-Id: I9806368bed426469b511e6f7e046feedf2e754de

wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core