Given a D 69 that's pending review, running arc patch D69 currently creates branch arcpatch-D69. Then, after the diff is updated by the author and the reviewer wants to see the updated changes, a consecutive arc patch D69 creates arcpatch-D69_1. This happens up to arcpatch-D69_3.
After that, it fails saying "Arc was unable to automagically make a name for this patch. Please clean up your working copy and try again.".
The solution is to just delete those previous branches, but shouldn't consecutive arc patch calls pull the updated diff for D 69 into the existing arcpatch-D69 every time? This is on Windows 8.1, current arcanist + libphutils.
>>> [17] <exec> $ git rev-parse --verify "arcpatch-D69"
<<< [17] <exec> 988,148 us
Branch name arcpatch-D69 already exists; trying a new name.
>>> [18] <exec> $ git rev-parse --verify "arcpatch-D69_1"
<<< [18] <exec> 584,228 us
Branch name arcpatch-D69_1 already exists; trying a new name.
>>> [19] <exec> $ git rev-parse --verify "arcpatch-D69_2"
<<< [19] <exec> 574,197 us
Branch name arcpatch-D69_2 already exists; trying a new name.
>>> [20] <exec> $ git rev-parse --verify "arcpatch-D69_3"
<<< [20] <exec> 172,490 us
Branch name arcpatch-D69_3 already exists; trying a new name.
[2016-01-13 15:19:27] EXCEPTION: (Exception) Arc was unable to automagically make a name for this patch. Please clean up your working copy and try again. at [<arcanist>\src\workflow\ArcanistPatchWorkflow.php:250]
arcanist(head=master, ref.master=05c12eb9d9cb), phutil(head=master, ref.master=0fa7efbf09d7)
#0 ArcanistPatchWorkflow::getBranchName(ArcanistBundle) called at [<arcanist>\src\workflow\ArcanistPatchWorkflow.php:303]
#1 ArcanistPatchWorkflow::createBranch(ArcanistBundle, boolean) called at [<arcanist>\src\workflow\ArcanistPatchWorkflow.php:453]
#2 ArcanistPatchWorkflow::run() called at [<arcanist>\src\workflow\ArcanistPatchWorkflow.php:397]
#3 ArcanistPatchWorkflow::run() called at [<arcanist>\scripts\arcanist.php:392]