I was hitting the following error when attempting to use ./bin/lipsum generate:
[2015-02-28 21:55:00] ERROR 2: array_rand(): Second argument has to be between 1 and the number of elements in the array at [/usr/src/phabricator/src/applications/pholio/lipsum/PhabricatorPholioMockTestDataGenerator.php:93] arcanist(head=master, ref.master=d8182cf55d50), phabricator(head=master, ref.master=658175925931), phutil(head=master, ref.master=260e6105dee5) #0 array_rand(array, integer) called at [<phabricator>/src/applications/pholio/lipsum/PhabricatorPholioMockTestDataGenerator.php:93] #1 PhabricatorPholioMockTestDataGenerator::generateImages() called at [<phabricator>/src/applications/pholio/lipsum/PhabricatorPholioMockTestDataGenerator.php:30] #2 PhabricatorPholioMockTestDataGenerator::generate() called at [<phabricator>/src/applications/lipsum/management/PhabricatorLipsumGenerateWorkflow.php:67] #3 PhabricatorLipsumGenerateWorkflow::infinitelyGenerate(array) called at [<phabricator>/src/applications/lipsum/management/PhabricatorLipsumGenerateWorkflow.php:36] #4 PhabricatorLipsumGenerateWorkflow::execute(PhutilArgumentParser) called at [<phutil>/src/parser/argument/PhutilArgumentParser.php:396] #5 PhutilArgumentParser::parseWorkflowsFull(array) called at [<phutil>/src/parser/argument/PhutilArgumentParser.php:292] #6 PhutilArgumentParser::parseWorkflows(array) called at [<phabricator>/scripts/lipsum/manage_lipsum.php:21]