Summary:
This is mainly to address the same issue as D3609747: prevent issues caused
by running hg as root. The difference is this extension reads owner and uid
dynamically without config when initializing of a localrepo object.
As a side effect it covers more situations like running hg in others' repos, while
being less restrictive for some other commands like `sudo hg version`.
Test Plan: Added a new test
Reviewers: #mercurial, ttung, rmcelroy
Reviewed By: rmcelroy
Subscribers: ikostia, rmcelroy, mjpieters
Differential Revision: https://phabricator.intern.facebook.com/D3619997
Tasks: 11723374
Signature: t1:3619997:1470176448:beaf53c09fca498206767641ffa4315a744ee07e