HearbeatFuture: Use correct timeout in error message

The timeout argument in `wait` tells how much we need to wait taking
into consideration that we already waited for some other futures.
This created confusing hearbeat messages, that could even show negative
wait times.

Author: Lorak-mmk

cassandra/connection.py

@@ -1821,15 +1821,15 @@ def __init__(self, connection, owner):
                 self._exception = Exception("Failed to send heartbeat because connection 'in_flight' exceeds threshold")
                 self._event.set()
 
-    def wait(self, timeout):
+    def wait(self, timeout, original_timeout):
         self._event.wait(timeout)
         if self._event.is_set():
             if self._exception:
                 raise self._exception
         else:
-            raise OperationTimedOut("Connection heartbeat timeout after %s seconds" % (timeout,),
+            raise OperationTimedOut("Connection heartbeat timeout after %s seconds" % (original_timeout,),
                                     self.connection.endpoint,
-                                    timeout=timeout,
+                                    timeout=original_timeout,
                                     in_flight=self.connection.in_flight)
 
     def _options_callback(self, response):
@@ -1894,7 +1894,7 @@ def run(self):
                     self._raise_if_stopped()
                     connection = f.connection
                     try:
-                        f.wait(timeout_left)
+                        f.wait(timeout_left, self._timeout)
                         # TODO: move this, along with connection locks in pool, down into Connection
                         with connection.lock:
                             connection.in_flight -= 1