title: Php datastore script fails on development server while runs as expected on production server
body: <p>Have a look on the following datastore script:</p>
  
  <pre><code>&lt;?php
  use google\appengine\datastore\v4\Mutation\Operation;
  use google\appengine\datastore\v4\BeginTransactionRequest;
  use google\appengine\datastore\v4\BeginTransactionResponse;
  use google\appengine\datastore\v4\CommitRequest;
  use google\appengine\datastore\v4\CommitRequest\Mode;
  use google\appengine\datastore\v4\CommitResponse;
  use google\appengine\datastore\v4\RollbackRequest;
  use google\appengine\datastore\v4\RollbackResponse;
  use google\appengine\runtime\ApiProxy;
  use google\appengine\runtime\ApplicationError;
  
  
  function beginTransaction(){
      global $request, $response;
      $request = new BeginTransactionRequest();
      $request-&gt;setCrossGroup(true);
      $response = new BeginTransactionResponse();
      try{
          ApiProxy::makeSyncCall('datastore_v4', 'BeginTransaction', $request, $response, 60);
      }
      catch(ApplicationError $e){
          echo $e-&gt;getMessage();
          exit();
      }
  
      $request = new CommitRequest();
      $request-&gt;setTransaction($response-&gt;transaction);
      $request-&gt;setMode(Mode::TRANSACTIONAL);
  }
  
  function prepareEntity($entity, $name, $author, $channel){
      global $projectId;
      $entity-&gt;mutableKey()-&gt;mutablePartitionId()-&gt;setDatasetId($projectId);
      $entity-&gt;mutableKey()-&gt;addPathElement()-&gt;setKind('Books');
      $entity-&gt;addProperty()-&gt;setName('Name')-&gt;mutableValue()-&gt;setStringValue($name);
      $entity-&gt;addProperty()-&gt;setName('Author')-&gt;mutableValue()-&gt;setStringValue($author);
      $entity-&gt;addProperty()-&gt;setName('Channel')-&gt;mutableValue()-&gt;setStringValue($channel);
  }
  
  function commit(){ 
      global $request, $response;
      $response = new CommitResponse();     
      try{
          ApiProxy::makeSyncCall('datastore_v4', 'Commit', $request, $response, 60);
      }
      catch(ApplicationError $e){
          echo $e-&gt;getMessage();
          exit();
      }
  }
  
  
  $projectId = $_SERVER['APPLICATION_ID'];
  beginTransaction();
  
  prepareEntity(
      $request-&gt;addMutation()-&gt;setOp(Operation::INSERT)-&gt;mutableEntity(),
      'Contemporary Abstract Algebra',
      'J Gallian',
      'Mutation'
      );
  
  prepareEntity(
      $request-&gt;addMutation()-&gt;setOp(Operation::INSERT)-&gt;mutableEntity(),
      'Principals of Mathematical Analysis',
      'Rudin',
      'Mutation'
      );
  commit('Mutation Commit');
  echo "&lt;h2&gt;Mutation Commit&lt;/h2&gt;";
  foreach($response-&gt;getMutationResultList() as $mutationResult){
      echo 'Book@'. end($mutationResult-&gt;getKey()-&gt;getPathElementList())-&gt;getId(). '&lt;br/&gt;';
  }
  echo '&lt;hr/&gt;';
  
  beginTransaction();
  prepareEntity(
      $request-&gt;mutableDeprecatedMutation()-&gt;addInsertAutOId(),
      'Contemporary Abstract Algebra',
      'J Gallian',
      'Deprecated Mutation'
      );
  
  prepareEntity(
      $request-&gt;mutableDeprecatedMutation()-&gt;addInsertAutOId(),
      'Principals of Mathematical Analysis',
      'Rudin',
      'Deprecated Mutation'
      );
  
  commit();
  echo "&lt;h2&gt;Deprecated Mutation Commit&lt;/h2&gt;";
  foreach($response-&gt;getDeprecatedMutationResult()-&gt;getInsertAutoIdKeyList() as $key){
      echo 'Book@'. end($key-&gt;getPathElementList())-&gt;getId(). '&lt;br/&gt;';
  }
  echo '&lt;hr/&gt;';
  </code></pre>
  
  <p>In this script the commits using mutation don't work on the development server. Neither they save the data nor they throw any error. Though they work as expected on the production server. The deprecated mutations work as expected on both development server and production server. I debugged and found that <code>make_call</code> function call in use google\appengine\runtime\RealApiProxy is unable to produce a response. Can someone please explain this behavior. Is that a bug in the development runtime?</p>