D8021: chg: switch to using global `environ` instead of envp from main

[martinvonz (Martin von Zweigbergk)]

martinvonz added a comment.


  Queuing based on @yuja's review.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D8021/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D8021

To: spectral, #hg-reviewers
Cc: martinvonz, yuja, pulkit, mercurial-devel