Fixed request packet receipts timing out in spite of delivery.

RNS/Packet.py

@@ -440,7 +440,7 @@ class PacketReceipt:
         return (self.sent_at+self.timeout < time.time())
 
     def check_timeout(self):
-        if self.is_timed_out():
+        if self.status == PacketReceipt.SENT and self.is_timed_out():
             if self.timeout == -1:
                 self.status = PacketReceipt.CULLED
             else:

RNS/Transport.py

@@ -864,6 +864,9 @@ class Transport:
                             if receipt.hash == proof_hash:
                                 receipt_validated = receipt.validate_proof_packet(packet)
                         else:
+                            # TODO: This looks like it should actually
+                            # be rewritten when implicit proofs are added.
+                            
                             # In case of an implicit proof, we have
                             # to check every single outstanding receipt
                             receipt_validated = receipt.validate_proof_packet(packet)