Martin von Zweigbergk <martinvonz@google.com> [Fri, 10 Jan 2020 13:24:25 -0800] rev 44052
workingctx: move setparents() logic from localrepo to mirror overlayworkingctx
It would be nice to later be able to call `wctx.setparents()` whether
`wctx` is a `workingctx` or an `overlayworkingctx`.
Differential Revision: https://phab.mercurial-scm.org/D7823