I just saw this in our error logs:
```
[18-Mar-2015 07:48:27 Australia/Sydney] [2015-03-18 07:48:27] EXCEPTION: (Exception) Transaction type 'differential:action' is missing an internal apply implementation! at [<phabricator>/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php:501]
[18-Mar-2015 07:48:27 Australia/Sydney] arcanist(head=master, ref.master=b961869edac9), phabricator(head=master, ref.master=ca042df6deac), phlab(head=master, ref.master=87eadcb22404), phutil(head=master, ref.master=ce3959b4046f)
[18-Mar-2015 07:48:27 Australia/Sydney] #0 PhabricatorApplicationTransactionEditor::applyCustomInternalTransaction(DifferentialRevision, DifferentialTransaction) called at [<phabricator>/src/applications/differential/editor/DifferentialTransactionEditor.php:256]
[18-Mar-2015 07:48:27 Australia/Sydney] #1 DifferentialTransactionEditor::applyCustomInternalTransaction(DifferentialRevision, DifferentialTransaction) called at [<phabricator>/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php:400]
[18-Mar-2015 07:48:27 Australia/Sydney] #2 PhabricatorApplicationTransactionEditor::applyInternalEffects(DifferentialRevision, DifferentialTransaction) called at [<phabricator>/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php:703]
[18-Mar-2015 07:48:27 Australia/Sydney] #3 PhabricatorApplicationTransactionEditor::applyTransactions(DifferentialRevision, array) called at [<phabricator>/src/applications/differential/controller/DifferentialCommentSaveController.php:124]
[18-Mar-2015 07:48:27 Australia/Sydney] #4 DifferentialCommentSaveController::processRequest() called at [<phabricator>/src/aphront/AphrontController.php:33]
[18-Mar-2015 07:48:27 Australia/Sydney] #5 AphrontController::handleRequest(AphrontRequest) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:196]
[18-Mar-2015 07:48:27 Australia/Sydney] #6 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:121]
[18-Mar-2015 07:48:27 Australia/Sydney] #7 AphrontApplicationConfiguration::runHTTPRequest(AphrontPHPHTTPSink) called at [<phabricator>/webroot/index.php:19]
```