Build status stayed ad building
```
Warning: Uncaught exception 'RuntimeException' with message 'Undefined variable: buildable' in /Users/cramer/Development/libphutil/src/error/PhutilErrorHandler.php:211
Stack trace:
#0 /Users/cramer/Development/pytest-phabricator/support/applications/changes/step/ChangesBuildStepImplementation.php(42): PhutilErrorHandler::handleError(8, 'Undefined varia...', '/Users/cramer/D...', 42, Array)
#1 /Users/cramer/Development/phabricator/src/applications/harbormaster/worker/HarbormasterBuildWorker.php(53): ChangesBuildStepImplementation->execute(Object(HarbormasterBuild), Object(HarbormasterBuildStep))
#2 /Users/cramer/Development/phabricator/src/infrastructure/daemon/workers/PhabricatorWorker.php(84): HarbormasterBuildWorker->doWork()
#3 /Users/cramer/Development/phabricator/src/infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php(122): PhabricatorWorker->executeTask()
#4 /Users/cramer/Development/phabricator/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php(19): PhabricatorWorkerActiveTask-> in /Users/cramer/Development/libphutil/src/error/PhutilErrorHandler.php on line 211
Fatal error: Call to a member function getBuildableObject() on a non-object in /Users/cramer/Development/pytest-phabricator/support/applications/changes/step/ChangesBuildStepImplementation.php on line 42
```