session: Fix ssh_free() with NULL argument.
session: Fix ssh_free() with NULL argument.

taikoo/libssh,pouete/libssh,wangshawn/libssh,DouglasHeriot/libssh,mwgoldsmith/ssh,sebadoom/libssh,nviennot/libssh,elastichosts/libssh,jt1/honeypot-libssh,nviennot/libssh,kedazo/libssh,nviennot/libssh,sebadoom/libssh,jt1/honeypot-libssh,kedazo/libssh,mwgoldsmith/libssh,Distrotech/libssh,pouete/libssh,taikoo/libssh,mwgoldsmith/libssh,DouglasHeriot/libssh,bigcat26/libssh-mod,sebadoom/libssh,mwgoldsmith/libssh,mwgoldsmith/libssh,wangshawn/libssh,DouglasHeriot/libssh,robxu9/libssh,mwgoldsmith/ssh,kedazo/libssh,robxu9/libssh,robxu9/libssh,taikoo/libssh,DouglasHeriot/libssh,pouete/libssh,bigcat26/libssh-mod,jt1/honeypot-libssh,sebadoom/libssh,nviennot/libssh,Distrotech/libssh,mwgoldsmith/ssh,wangshawn/libssh,robxu9/libssh,elastichosts/libssh,bigcat26/libssh-mod,Distrotech/libssh,elastichosts/libssh,taikoo/libssh,bigcat26/libssh-mod,pouete/libssh,jt1/honeypot-libssh,mwgoldsmith/ssh,kedazo/libssh,Distrotech/libssh,wangshawn/libssh