obsexc: use the common discovery We drop the hand made discovery and rely on the general one introduced some time ago.

obsexc: push nothing if push fail This is closer to the future behavior with bundle2.

discovery: hook on the official discovery for obsmarker This will let the discovery be done once and used by core.

discovery: use a different setup step for discovery This will ease the dropping of the other part later.

evolve: remove unused drop random

obshash: resist to unknown revision during discovery

code movement: gather discovery code together The discovery code is the one thing that will survive the great purge.

bundle2: drop custom compat We'll rely on the core implementation to use bundle2.

drop relevant marker compat

evolve: always use the transaction version of phase movement This drop compat with all known released version of Mercurial.