Problem: receive methods don't handle interrupt
Problem: receive methods don't handle interrupt

Solution: if msg is NULL, return and don't process it further.

c-rack/zproto,bkmit/zproto,somdoron/zproto,vyskocilm/zproto,bkmit/zproto,bkmit/zproto,c-rack/zproto,sappo/zproto,jemc/zproto,sappo/zproto,sphaero/zproto,sappo/zproto,jdiez17/zproto,sphaero/zproto,asokoloski/zproto,jemc/zproto,c-rack/zproto,jdiez17/zproto,zeromq/zproto,asokoloski/zproto,c-rack/zproto,zeromq/zproto,c-rack/zproto,vyskocilm/zproto,asokoloski/zproto,jdiez17/zproto,jemc/zproto,sappo/zproto,jemc/zproto,c-rack/zproto,jemc/zproto,hintjens/zproto,sappo/zproto,sphaero/zproto,bkmit/zproto,sappo/zproto,jdiez17/zproto,sappo/zproto,jemc/zproto,zeromq/zproto,zeromq/zproto,bkmit/zproto,somdoron/zproto,vyskocilm/zproto,somdoron/zproto,jdiez17/zproto,asokoloski/zproto,somdoron/zproto,zeromq/zproto,sphaero/zproto,hintjens/zproto,vyskocilm/zproto,zeromq/zproto,vyskocilm/zproto,bkmit/zproto,bkmit/zproto,zeromq/zproto,hintjens/zproto,hintjens/zproto,vyskocilm/zproto,asokoloski/zproto,somdoron/zproto,jemc/zproto,hintjens/zproto,hintjens/zproto,hintjens/zproto,somdoron/zproto,c-rack/zproto,vyskocilm/zproto,jdiez17/zproto,asokoloski/zproto,sphaero/zproto,somdoron/zproto,sphaero/zproto,asokoloski/zproto,jdiez17/zproto