D358: copytrace: move fb extension to core under flag experimental.fastcopytrace

[stash (Stanislau Hlebik)]

stash added a comment.


  Quick heads-up: one of our bootcampers works on the task that does the following: if rebase/merge/graft happens only on the local stack (i.e. base commit is draft), then we fallback to the normal copytrace, because we are sure it's going to be fast enough

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D358

To: pulkit, #hg-reviewers
Cc: quark, stash, mercurial-devel