Prevent empty warnings in case of certificate verification failures
Prevent empty warnings in case of certificate verification failures

Fixes #1976

w495/scrapy,eLRuLL/scrapy,kmike/scrapy,jc0n/scrapy,wenyu1001/scrapy,GregoryVigoTorres/scrapy,elacuesta/scrapy,Ryezhang/scrapy,GregoryVigoTorres/scrapy,redapple/scrapy,rolando/scrapy,rootAvish/scrapy,Ryezhang/scrapy,pablohoffman/scrapy,rolando-contrib/scrapy,taito/scrapy,foromer4/scrapy,dracony/scrapy,ssteo/scrapy,darkrho/scrapy-scrapy,Ryezhang/scrapy,barraponto/scrapy,Parlin-Galanodel/scrapy,scrapy/scrapy,Parlin-Galanodel/scrapy,ssteo/scrapy,arush0311/scrapy,w495/scrapy,elacuesta/scrapy,redapple/scrapy,eLRuLL/scrapy,wujuguang/scrapy,dracony/scrapy,dangra/scrapy,ArturGaspar/scrapy,finfish/scrapy,rootAvish/scrapy,barraponto/scrapy,starrify/scrapy,umrashrf/scrapy,ssteo/scrapy,finfish/scrapy,rolando/scrapy,arush0311/scrapy,scrapy/scrapy,starrify/scrapy,dangra/scrapy,rolando-contrib/scrapy,foromer4/scrapy,dracony/scrapy,pablohoffman/scrapy,foromer4/scrapy,Parlin-Galanodel/scrapy,shaform/scrapy,darkrho/scrapy-scrapy,jc0n/scrapy,jc0n/scrapy,dangra/scrapy,shaform/scrapy,YeelerG/scrapy,starrify/scrapy,carlosp420/scrapy,kmike/scrapy,wenyu1001/scrapy,taito/scrapy,scrapy/scrapy,umrashrf/scrapy,rolando/scrapy,wujuguang/scrapy,eLRuLL/scrapy,darkrho/scrapy-scrapy,carlosp420/scrapy,carlosp420/scrapy,barraponto/scrapy,crasker/scrapy,finfish/scrapy,redapple/scrapy,taito/scrapy,kmike/scrapy,arush0311/scrapy,shaform/scrapy,cyberplant/scrapy,pawelmhm/scrapy,w495/scrapy,crasker/scrapy,rolando-contrib/scrapy,pawelmhm/scrapy,pablohoffman/scrapy,YeelerG/scrapy,wenyu1001/scrapy,cyberplant/scrapy,ArturGaspar/scrapy,GregoryVigoTorres/scrapy,rootAvish/scrapy,crasker/scrapy,elacuesta/scrapy,cyberplant/scrapy,pawelmhm/scrapy,YeelerG/scrapy,umrashrf/scrapy,ArturGaspar/scrapy,wujuguang/scrapy