tests/test-empty.t

wireprotov2: send protocol settings frame from client

Now that we have client and server reactor support for protocol
settings and encoding frames, we can start to send them out over
the wire!

This commit teaches the client reactor to send out a protocol
settings frame when needed. The httpv2 peer has been taught to
gather a list of supported content encoders and to advertise them
through the client reactor.

Because the client is now sending new frame types by default, this
constitutes a compatibility break in the framing protocol. The
media type version has been bumped accordingly. This will ensure
existing clients won't attempt to send the new frames to old
servers not supporting this explicit media type. I'm not bothering
with the BC annotation because everything wireprotov2 is highly
experimental and nobody should be running a server yet.

Differential Revision: https://phab.mercurial-scm.org/D4922

Create an empty repo:

  $ hg init a
  $ cd a

Try some commands:

  $ hg log
  $ hg grep wah
  [1]
  $ hg manifest
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 0 changesets with 0 changes to 0 files

Check the basic files created:

  $ ls .hg
  00changelog.i
  requires
  store

Should be empty:

  $ ls .hg/store

Poke at a clone:

  $ cd ..
  $ hg clone a b
  updating to branch default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd b
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 0 changesets with 0 changes to 0 files
  $ ls .hg
  00changelog.i
  hgrc
  requires
  store

Should be empty:

  $ ls .hg/store

  $ cd ..