I'm seeing a couple of these in our error logs:
```
[06-Mar-2015 11:01:10 Australia/Sydney] [2015-03-06 11:01:10] ERROR 2: Invalid argument supplied for foreach() at [/usr/src/phabricator/src/applications/differential/cust
omfield/DifferentialReviewersField.php:190]
omfield/DifferentialReviewersField.php:190][06-Mar-2015 11:01:10 Australia/Sydney] arcanist(head=master, ref.master=c36b4ceb1849), phabricator(head=master, ref.master=9564b0a40e88), phlab(head=master, ref.master=4689d11dbe69), phutil(head=master, ref.master=eaa6ebecef8e)
[06-Mar-2015 11:01:10 Australia/Sydney]
arcanist(head=master, ref.master=c36b4ceb1849), phabricator(head=master, ref.master=9564b0a40e88), phlab(head=master, ref.master=4 #0 DifferentialReviewersField::validateCommitMessageValue(NULL) called at [<phabricator>/src/applications/differential/conduit/DifferentialParseCommitMessageConduitAPIMethod.php:74]
689d11dbe69), phutil(head=master, ref.master=eaa6ebecef8e)[06-Mar-2015 11:01:10 Australia/Sydney] #1 DifferentialParseCommitMessageConduitAPIMethod::execute(ConduitAPIRequest) called at [<phabricator>/src/applications/conduit/method/ConduitAPIMethod.php:65]
[06-Mar-2015 11:01:10 Australia/Sydney]
#0 DifferentialReviewersField::validateCommitMessageValue(NULL) called at [<phabricator>/src/applications/differential/conduit/D
ifferentialParseCommitMessageConduitAPIMethod.php:74]
[06-Mar-2015 11:01:10 Australia/Sydney] #1 DifferentialParseCommitMessageConduitAPIMethod::execute(ConduitAPIRequest) called at [<phabricator>/src/applications/conduit/
method/ConduitAPIMethod.php:65]
[06-Mar-2015 11:01:10 Australia/Sydney] #2 ConduitAPIMethod::executeMethod(ConduitAPIRequest) called at [<phabricator>/src/applications/conduit/call/ConduitCall.php:134
]
[06-Mar-2015 11:01:10 Australia/Sydney] #3 ConduitCall::executeMethod() called at [<phabricator>/src/applications/conduit/call/ConduitCall.php:84]
[06-Mar-2015 11:01:10 Australia/Sydney] #4 ConduitCall::execute() called at [<phabricator>/src/applications/conduit/controller/PhabricatorConduitAPIController.php:88]
[06-Mar-2015 11:01:10 Australia/Sydney] #5 PhabricatorConduitAPIController::processRequest() called at [<phabricator>/src/aphront/AphrontController.php:33]
[06-Mar-2015 11:01:10 Australia/Sydney] #6 AphrontController::handleRequest(AphrontRequest) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfigu
ration.php:196]
[06-Mar-2015 11:01:10 Australia/Sydney] #7 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink) called at [<phabricato
[06-Mar-2015 11:01:10 Australia/Sydney] #7 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:121]
[06-Mar-2015 11:01:10 Australia/Sydney] #8 AphrontApplicationConfiguration::runHTTPRequest(AphrontPHPHTTPSink) called at [<phabricator>/webroot/index.php:19]
```