API-based search: [] means /every/ namespace, not just 0
API-based search: [] means /every/ namespace, not just 0

In the scrape-based search, the namespaces=[] parameter meant to search /every/
namespace, not just 0. This commit adapts the API search behavior to be
consistent with this.


https://mediawiki.org/wiki/Special:Code/pywikipedia/11380

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