fixed possible crash when enabling multiple connections per IP

ChangeLog

@@ -1,4 +1,5 @@
 
+	* fixed possible crash when enabling multiple connections per IP
 	* fixed typo in win vista specific code, breaking the build
 	* change default of rate_limit_utp to true
 	* fixed DLL export issue on windows (when building a shared library linking statically against boost)

src/policy.cpp

@@ -1029,6 +1029,14 @@ namespace libtorrent
 					pp.source |= src;
 					if (!was_conn_cand && is_connect_candidate(pp, m_finished))
 						++m_num_connect_candidates;
+					// calling disconnect() on a peer, may actually end
+					// up "garbage collecting" its policy::peer entry
+					// as well, if it's considered useless (which this specific)
+					// case will, since it was an incoming peer that just disconnected
+					// and we allow multiple connections per IP. Because of that,
+					// we need to make sure we don't let it do that, by unlinking
+					// the peer_connection from the policy::peer first.
+					p->connection->set_peer_info(0);
 					p->connection->disconnect(errors::duplicate_peer_id);
 					erase_peer(p);
 					return false;