Don't crash if PUBKEY is not set when using SIGNATURE_TYPE:PUBKEY
Don't crash if PUBKEY is not set when using SIGNATURE_TYPE:PUBKEY

Reported by:	RootWyrm on freenode

Open343/pkg,en90/pkg,skoef/pkg,junovitch/pkg,Open343/pkg,khorben/pkg,khorben/pkg,khorben/pkg,en90/pkg,junovitch/pkg,skoef/pkg