Martin von Zweigbergk <martinvonz@google.com> [Fri, 27 Dec 2019 13:03:40 -0800] rev 44089
graft: extract repo[None] to a variable
I plan to allow the caller pass in an overlayworkingctx, so this
prepares for that.
Differential Revision: https://phab.mercurial-scm.org/D7857