UnknownExtension: subclass of NotImplementedError
UnknownExtension: subclass of NotImplementedError

Introduced in f49ea26af91a72e5143a55cfe28be07c2888edb6 as subclass of
SiteDefinitionError.

Change-Id: I0ec77160c3f3f583369b90e0319022905a5ad506

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