message: Fix dedupExchange affecting mutations
  We never want mutations to be deduplicated, not even
  when they're in-flight. Instead we're assuming that
  duplicate mutations are intentional.
diff: @@ -7,7 +7,12 @@ export const dedupExchange = (forward: IExchange): IExchange => {
  const inFlight = {};
  return operation => {
  - const { key } = operation;
  + const { key, operationName } = operation;
  +
  + // Do not try to deduplicate mutation operations
  + if (operationName === 'mutation') {
  + return forward(operation);
  + }
  // Take existing intermediate observable if it has been created
  if (inFlight[key] !== undefined) {
  