Must update pending_transactions map before yield'ing

synapse/federation/transaction_queue.py

@@ -224,6 +224,8 @@ class TransactionQueue(object):
         ]
 
         try:
+            self.pending_transactions[destination] = 1
+
             limiter = yield get_retry_limiter(
                 destination,
                 self._clock,
@@ -239,8 +241,6 @@ class TransactionQueue(object):
                 len(pending_failures)
             )
 
-            self.pending_transactions[destination] = 1
-
             logger.debug("TX [%s] Persisting transaction...", destination)
 
             transaction = Transaction.create_new(