An install reported hitting this:
[2016-10-25 20:48:04] EXCEPTION: (ConduitClientException) ERR-CONDUIT-CORE: [HTTP/500] Internal Server Error\n>>> UNRECOVERABLE FATAL ERROR <<<\n\nMaximum execution time of 30 seconds exceeded\n\n<...>/phabricator/src/applications/repository/graphcache/PhabricatorRepositoryGraphCache.php:390\n\n\n\xe2\x94\xbb\xe2\x94\x81\xe2\x94\xbb \xef\xb8\xb5 \xc2\xaf\\_(\xe3\x83\x84)_/\xc2\xaf \xef\xb8\xb5 \xe2\x94\xbb\xe2\x94\x81\xe2\x94\xbb at [<phutil>/src/conduit/ConduitFuture.php:58] <...> #0 <#2> ConduitFuture::didReceiveResult(array) called at [<phutil>/src/future/FutureProxy.php:58] #1 <#2> FutureProxy::getResult() called at [<phutil>/src/future/FutureProxy.php:35] #2 <#2> FutureProxy::resolve() called at [<phutil>/src/conduit/ConduitClient.php:64] #3 <#2> ConduitClient::callMethodSynchronous(string, array) called at [<phabricator>/src/applications/diffusion/conduit/DiffusionQueryConduitAPIMethod.php:137] #4 <#2> DiffusionQueryConduitAPIMethod::execute(ConduitAPIRequest) called at [<phabricator>/src/applications/conduit/method/ConduitAPIMethod.php:122] #5 <#2> ConduitAPIMethod::executeMethod(ConduitAPIRequest) called at [<phabricator>/src/applications/conduit/call/ConduitCall.php:131] #6 <#2> ConduitCall::executeMethod() called at [<phabricator>/src/applications/conduit/call/ConduitCall.php:81] #7 <#2> ConduitCall::execute() called at [<phabricator>/src/applications/conduit/controller/PhabricatorConduitAPIController.php:83] #8 phlog(ConduitClientException) called at [<phabricator>/src/applications/conduit/controller/PhabricatorConduitAPIController.php:103] #9 PhabricatorConduitAPIController::handleRequest(AphrontRequest) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:257] #10 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink, MultimeterControl) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:169] #11 AphrontApplicationConfiguration::runHTTPRequest(AphrontPHPHTTPSink) called at [<phabricator>/webroot/index.php:17]