upstream commit

Fix bug introduced in rev 1.467 which causes
"buffer_get_bignum_ret: incomplete message" errors when built with WITH_SSH1
and run such that no Protocol 1 ephemeral host key is generated (eg "Protocol
2", no SSH1 host key supplied).  Reported by rainer.laatsch at t-online.de,
ok deraadt@

Upstream-ID: aa6b132da5c325523aed7989cc5a320497c919dc
