D2593: state: add logic to parse the state file in old way if cbor fails

[indygreg (Gregory Szorc)]

indygreg added a comment.


  Not sure where to record this comment in this series. So I'll pick this commit.
  
  I think we want an explicit version header in the state files so clients know when they may be reading a file in an old format. For example, if I start a merge in one terminal window, I sometimes move to another terminal window to resolve parts of it. The multiple windows may be running different Mercurial versions. For example, sometimes one of the shells has a virtualenv activated and that virtualenv is running an older Mercurial. We don't want the older Mercurial trampling on state needed by the new Mercurial.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2593

To: pulkit, #hg-reviewers
Cc: indygreg, durin42, mercurial-devel