Fix bug 1659: set correct language as source
Fix bug 1659: set correct language as source

Because the variable 'lang' was used for two different meanings,
the saved language was whatever was read last from the json
configuration.

Change-Id: I2abd7311f6d534f71ffdbec44c80138966d70e1c

magul/pywikibot-core,TridevGuha/pywikibot-core,npdoty/pywikibot,emijrp/pywikibot-core,wikimedia/pywikibot-core,jayvdb/pywikibot-core,happy5214/pywikibot-core,darthbhyrava/pywikibot-local,wikimedia/pywikibot-core,h4ck3rm1k3/pywikibot-core,icyflame/batman,hasteur/g13bot_tools_new,VcamX/pywikibot-core,jayvdb/pywikibot-core,h4ck3rm1k3/pywikibot-core,magul/pywikibot-core,npdoty/pywikibot,hasteur/g13bot_tools_new,Darkdadaah/pywikibot-core,xZise/pywikibot-core,happy5214/pywikibot-core,valhallasw/pywikibot-core,trishnaguha/pywikibot-core,Darkdadaah/pywikibot-core,PersianWikipedia/pywikibot-core,hasteur/g13bot_tools_new,smalyshev/pywikibot-core