bail after, not at, max size

synapse/http/client.py

@@ -1034,7 +1034,7 @@ def dataReceived(self, data: bytes) -> None:
         # The first time the maximum size is exceeded, error and cancel the
         # connection. dataReceived might be called again if data was received
         # in the meantime.
-        if self.max_size is not None and self.length >= self.max_size:
+        if self.max_size is not None and self.length > self.max_size:
             self.deferred.errback(BodyExceededMaxSize())
             # Close the connection (forcefully) since all the data will get
             # discarded anyway.