tests/test-unbundlehash.t

interfaces: introduce and use a protocol class for the `charencoding` module

See f2832de2a46c for details when this was done for the `bdiff` module.

This lets us dump the hack where the `pure` implementation was imported during
the type checking phase to provide signatures for the module methods it
provides.  Now the protocol classes are starting to shine, because these methods
are provided by `pure.charencoding` and `cext.parsers`, and references to
`cffi.charencoding` and `cext.charencoding` are forwarded to them as appropriate
by the `policy` module.  But none of that matters, as long as the module
returned provides the listed methods.

The interface was copy/pasted from the `pure` module, but `jsonescapeu8fallback`
is omitted because it is accessed from the `pure` module directly when the
escaping fails in the primary module's `jsonescapeu8()`.

Test wire protocol unbundle with hashed heads (capability: unbundlehash)

  $ cat << EOF >> $HGRCPATH
  > [devel]
  > # This tests is intended for bundle1 only.
  > # bundle2 carries the head information inside the bundle itself and
  > # always uses 'force' as the heads value.
  > legacy.exchange = bundle1
  > EOF

Create a remote repository.

  $ hg init remote
  $ hg serve -R remote --config web.push_ssl=False --config web.allow_push=* -p $HGPORT -d --pid-file=hg1.pid -E error.log -A access.log
  $ cat hg1.pid >> $DAEMON_PIDS

Clone the repository and push a change.

  $ hg clone http://localhost:$HGPORT/ local
  no changes found
  updating to branch default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ touch local/README
  $ hg ci -R local -A -m hoge
  adding README
  $ hg push -R local
  pushing to http://localhost:$HGPORT/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files

Ensure hashed heads format is used.
The hash here is always the same since the remote repository only has the null head.

  $ cat access.log | grep unbundle
  * - - [*] "POST /?cmd=unbundle HTTP/1.1" 200 - x-hgarg-1:heads=686173686564+6768033e216468247bd031a0a2d9876d79818f8f* (glob)

Explicitly kill daemons to let the test exit on Windows

  $ killdaemons.py