Just digging through our PHP logs and found this:
[28-Jul-2015 14:06:48 Australia/Sydney] [2015-07-28 14:06:48] ERROR 2: array_flip(): Can only flip STRING and INTEGER values! at [/usr/src/phabricator/src/applications/differential/parser/DifferentialChangesetParser.php:1099] [28-Jul-2015 14:06:48 Australia/Sydney] arcanist(head=master, ref.master=5e4f9a2bf9d2), phabricator(head=master, ref.master=3bfb43629602, custom=1), phlab(head=master, ref.master=76e00f2a51e8), phutil(head=master, ref.master=aa6cd8f7e5e5) [28-Jul-2015 14:06:48 Australia/Sydney] #0 array_flip(array) called at [<phabricator>/src/applications/differential/parser/DifferentialChangesetParser.php:1099] [28-Jul-2015 14:06:48 Australia/Sydney] #1 DifferentialChangesetParser::render(NULL, NULL, array) called at [<phabricator>/src/applications/differential/parser/DifferentialChangesetParser.php:72] [28-Jul-2015 14:06:48 Australia/Sydney] #2 DifferentialChangesetParser::renderChangeset() called at [<phabricator>/src/applications/differential/controller/DifferentialChangesetViewController.php:258] [28-Jul-2015 14:06:48 Australia/Sydney] #3 DifferentialChangesetViewController::handleRequest(AphrontRequest) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:226] [28-Jul-2015 14:06:48 Australia/Sydney] #4 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink, MultimeterControl) called at [<phabricator>/src/aphront/configuration/AphrontApplicationCon figuration.php:140] [28-Jul-2015 14:06:48 Australia/Sydney] #5 AphrontApplicationConfiguration::runHTTPRequest(AphrontPHPHTTPSink) called at [<phabricator>/webroot/index.php:21]