Just going through our error logs and saw a bunch of these, although I'm not exactly sure how to reproduce:
[25-Nov-2015 19:11:51 Australia/Sydney] [2015-11-25 19:11:51] ERROR 2: array_diff(): Argument #1 is not an array at [/usr/src/phabricator/src/applications/transactions/editfield/PhabricatorTokenizerEditField.php:53] [25-Nov-2015 19:11:51 Australia/Sydney] arcanist(head=master, ref.master=72d9013d29dc), phabricator(head=master, ref.master=2047483cc046, custom=1), phlab(head=master, ref.master=cd07327495c5), phutil(head=master, ref.master=5538909d6468) [25-Nov-2015 19:11:51 Australia/Sydney] #0 array_diff(NULL, array) called at [<phabricator>/src/applications/transactions/editfield/PhabricatorTokenizerEditField.php:53] [25-Nov-2015 19:11:51 Australia/Sydney] #1 PhabricatorTokenizerEditField::getValueForTransaction() called at [<phabricator>/src/applications/transactions/editfield/PhabricatorEditField.php:238] [25-Nov-2015 19:11:51 Australia/Sydney] #2 PhabricatorEditField::generateTransaction(PhabricatorPasteTransaction) called at [<phabricator>/src/applications/transactions/editengine/PhabricatorEditEngine.php:686] [25-Nov-2015 19:11:51 Australia/Sydney] #3 PhabricatorEditEngine::buildEditResponse(PhabricatorPaste) called at [<phabricator>/src/applications/transactions/editengine/PhabricatorEditEngine.php:633] [25-Nov-2015 19:11:51 Australia/Sydney] #4 PhabricatorEditEngine::buildResponse() called at [<phabricator>/src/applications/paste/controller/PhabricatorPasteEditController.php:8] [25-Nov-2015 19:11:51 Australia/Sydney] #5 PhabricatorPasteEditController::handleRequest(AphrontRequest) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:237] [25-Nov-2015 19:11:51 Australia/Sydney] #6 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink, MultimeterControl) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:149]