explicitly fail with a useful message
explicitly fail with a useful message

samv/pyopenssl,kjav/pyopenssl,aalba6675/pyopenssl,rackerlabs/pyopenssl,mitghi/pyopenssl,aalba6675/pyopenssl,mschmo/pyopenssl,rackerlabs/pyopenssl,Lukasa/pyopenssl,kediacorporation/pyopenssl,reaperhulk/pyopenssl,elitest/pyopenssl,kediacorporation/pyopenssl,mhils/pyopenssl,sorenh/pyopenssl,adamwolf/pyopenssl,reaperhulk/pyopenssl,sholsapp/pyopenssl,mitghi/pyopenssl,daodaoliang/pyopenssl,Lukasa/pyopenssl,mhils/pyopenssl,hynek/pyopenssl,r0ro/pyopenssl,hynek/pyopenssl,pyca/pyopenssl,JensTimmerman/pyopenssl,r0ro/pyopenssl,JensTimmerman/pyopenssl