Fix edit conflicts after calls to save_claim()
Fix edit conflicts after calls to save_claim()

Unlike DataSite.addClaim(), DataSite.save_claim() was not updating
the latest revision ID of the item of the saved claim. As a result,
any submission to Wikidata after modifying a claim, such as
Claim.changeRank(), would result in an edit conflict.

Now DataSite.save_claim() updates the latest revision ID of the
item of the saved claim.

Change-Id: I2079228b50abca2e171bbc63e6bdd581532cd703

h4ck3rm1k3/pywikibot-core,PersianWikipedia/pywikibot-core,npdoty/pywikibot,jayvdb/pywikibot-core,Darkdadaah/pywikibot-core,smalyshev/pywikibot-core,hasteur/g13bot_tools_new,hasteur/g13bot_tools_new,npdoty/pywikibot,jayvdb/pywikibot-core,magul/pywikibot-core,wikimedia/pywikibot-core,Darkdadaah/pywikibot-core,happy5214/pywikibot-core,hasteur/g13bot_tools_new,happy5214/pywikibot-core,wikimedia/pywikibot-core,magul/pywikibot-core,darthbhyrava/pywikibot-local,h4ck3rm1k3/pywikibot-core