[PATCH 2 of 2] exchange: check actually missing revs for obsolete / unstable revs (issue6372)

[Augie Fackler]

On Fri, Jul 17, 2020 at 08:27:27AM +0200, Manuel Jacob wrote:
> # HG changeset patch
> # User Manuel Jacob <me at manueljacob.de>
> # Date 1594966891 -7200
> #      Fri Jul 17 08:21:31 2020 +0200
> # Node ID 91c59e59daae6b4bc0fe86b09c01fcc2e1aace9d
> # Parent  55626b2da7d55766ae667d91652d094c0c4aa86f
> # EXP-Topic issue6372
> exchange: check actually missing revs for obsolete / unstable revs (issue6372)

These look reasonable, but need rebased.