[FIX] Config2: Don't decode user-config
[FIX] Config2: Don't decode user-config

It doesn't try to decode the user-config.py by itself but let compile()
handle a byte string. That does interpret the header in the file and
decode it accordingly.

Change-Id: I32b26e31d1d838d08d91b2c480d4800effb6995a

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