Clear stream-isolation state on rend circs if needed to attach streams

Fixes bug 4655; bugfix on 0.2.3.3-alpha.

changes/bug4655

@@ -0,0 +1,10 @@
+  o Minor bugfixes:
+
+    - If we can't attach streams to a rendezvous circuit when we
+      finish connecting to a hidden service, clear the rendezvous
+      circuit's stream-isolation state and try to attach streams
+      again.  Previously, we cleared rendezvous circuits' isolation
+      state either too early (if they were freshly built) or not at
+      all (if they had been built earlier and were cannibalized).
+      Bugfix on 0.2.3.3-alpha; fixes bug 4655.
+

src/or/rendclient.c

@@ -892,10 +892,12 @@ rend_client_receive_rendezvous(origin_circuit_t *circ, const uint8_t *request,
 
   onion_append_to_cpath(&circ->cpath, hop);
   circ->build_state->pending_final_cpath = NULL; /* prevent double-free */
+
   /* XXXX023 This is a pretty brute-force approach. It'd be better to
    * attach only the connections that are waiting on this circuit, rather
    * than trying to attach them all. See comments bug 743. */
-  connection_ap_attach_pending();
+  circuit_try_attaching_streams(circ);
+
   memset(keys, 0, sizeof(keys));
   return 0;
  err: