Minor tidying of `ArcanistVersionWorkflow`
Minor tidying of `ArcanistVersionWorkflow`

Summary: Self-explanatory.

Test Plan: Eyeball it.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11553

aik099/arcanist,coursera/arcanist,calblueprint/arcanist,r4nt/arcanist,memsql/arcanist,chundongwang/arcanist,wikimedia/phabricator-arcanist,KieranHayes/arcanist,kevinseelbach/arcanist,chundongwang/arcanist,Symplicity/arcanist,aik099/arcanist,Khan/arcanist,phacility/arcanist,hach-que/arcanist,zhihu/arcanist,eSpark/arcanist,haskell-infra/arcanist,wharris/arcanist,fivestars/arcanist,wxstars/arcanist,KieranHayes/arcanist,eSpark/arcanist,kevinseelbach/arcanist,PageUpPeopleOrg/arcanist-patches,alexmv/arcanist,coursera/arcanist,folsom-labs/arcanist,chundongwang/arcanist,Symplicity/arcanist,sneakpeeq/arcanist,fivestars/arcanist,PageUpPeopleOrg/arcanist-patches,kevinseelbach/arcanist,aik099/arcanist,jra3/arcanist,uber/arcanist,jra3/arcanist,uber/arcanist,hach-que/arcanist,sneakpeeq/arcanist,codelabs-ch/arcanist,Symplicity/arcanist,Khan/arcanist,phacility/arcanist,fivestars/arcanist,memsql/arcanist,codelabs-ch/arcanist,chundongwang/arcanist,codelabs-ch/arcanist,zhihu/arcanist,r4nt/arcanist,memsql/arcanist,phacility/arcanist,coursera/arcanist,phacility/arcanist,zhihu/arcanist,eSpark/arcanist,wharris/arcanist,folsom-labs/arcanist,r4nt/arcanist,folsom-labs/arcanist,jra3/arcanist,alexmv/arcanist,wikimedia/phabricator-arcanist,coursera/arcanist,sneakpeeq/arcanist,haskell-infra/arcanist,calblueprint/arcanist,kevinseelbach/arcanist,r4nt/arcanist,haskell-infra/arcanist,wxstars/arcanist,wxstars/arcanist,uber/arcanist,Khan/arcanist,wxstars/arcanist,Khan/arcanist,wikimedia/phabricator-arcanist,KieranHayes/arcanist,eSpark/arcanist,PageUpPeopleOrg/arcanist-patches,alexmv/arcanist,zhihu/arcanist,KieranHayes/arcanist,codelabs-ch/arcanist,folsom-labs/arcanist,codelabs-ch/arcanist,calblueprint/arcanist,hach-que/arcanist,aik099/arcanist,PageUpPeopleOrg/arcanist-patches,alexmv/arcanist,Symplicity/arcanist,calblueprint/arcanist,wikimedia/phabricator-arcanist,wharris/arcanist,memsql/arcanist,sneakpeeq/arcanist,jra3/arcanist,hach-que/arcanist,phacility/arcanist,haskell-infra/arcanist,wharris/arcanist,uber/arcanist,fivestars/arcanist