Make "arc which --show-base" work as expected
Make "arc which --show-base" work as expected

Summary: This is supposed to just print out the base revision, but actually prints out the repository section first.

Test Plan: Ran `arc which`, `arc which --show-base`.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D11888

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