ArcanistBundle: fix attribution of $old_phid when building binary changes
ArcanistBundle: fix attribution of $old_phid when building binary changes

Summary:
The variable $old_phid was not being set in a certain situation in
buildBinaryChange(), and that was causing the following error, during
`arc patch <revision>`:

"the patch applies to <file> (<hash>), which does not match the
current contents."

and hence it was failing to download/apply the patch.

Signed-off-by: Sergio Correia <sergio@correia.cc>

Test Plan:
I spotted the problem in a revision where I was renaming
some images, which are binary.

Reviewers: epriestley, vrana, btrahan

Reviewed By: btrahan

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3925

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