This makes conduit very angry:
[2015-07-14 00:34:05] EXCEPTION: (ConduitClientException) ERR-CONDUIT-CORE: Parameter 'duration' has invalid type. Expected type 'optional float|int', got type 'string'. at [<phutil>/src/conduit/ConduitFuture.php:58] arcanist(head=master, ref.master=999eb9376568), checkstyle(head=staging, ref.master=f6a32a631b72, ref.staging=6e17fd2acd7b), phutil(head=master, ref.master=aa6cd8f7e5e5) #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 [<arcanist>/src/workflow/ArcanistDiffWorkflow.php:2786] #3 phlog(ConduitClientException) called at [<arcanist>/src/workflow/ArcanistDiffWorkflow.php:2792] #4 ArcanistDiffWorkflow::updateAutotargets(string, integer) called at [<arcanist>/src/workflow/ArcanistDiffWorkflow.php:530] #5 ArcanistDiffWorkflow::run() called at [<arcanist>/scripts/arcanist.php:382]
This doesn't stop arc from running tests, lints or creating revisions, but it doesn't report the unit test results in Differential.