Minor tidying of `ArcanistRevertWorkflow`
Minor tidying of `ArcanistRevertWorkflow`

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/D11557

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