[IMPR] Simplify Revision.sha1
[IMPR] Simplify Revision.sha1

detached from 05da8018ecd9053e0be73594825deefcb6cca239

Change-Id: I9029cb802d27d34afd7d46b4b7ed894abd4f8f76

wikimedia/pywikibot-core,wikimedia/pywikibot-core