tests/test-wireproto-command-heads.t

help: add internals.extensions topic

I think it's better to include the API overview in core as we now have the
internals section in our help system.

Retrieved from the wiki, and formatted as reST. Several wiki links are
removed since they are invalid in the help. The sections about example
extension are removed at all as they seemed too verbose.

https://www.mercurial-scm.org/wiki/WritingExtensions

  $ . $TESTDIR/wireprotohelpers.sh

  $ hg init server
  $ enablehttpv2 server
  $ cd server
  $ hg debugdrawdag << EOF
  > H I J
  > | | |
  > E F G
  > | |/
  > C D
  > |/
  > B
  > |
  > A
  > EOF

  $ hg phase --force --secret J
  $ hg phase --public E

  $ hg log -r 'E + H + I + G + J' -T '{rev}:{node} {desc} {phase}\n'
  4:78d2dca436b2f5b188ac267e29b81e07266d38fc E public
  7:ae492e36b0c8339ffaf328d00b85b4525de1165e H draft
  8:1d6f6b91d44aaba6d5e580bc30a9948530dbe00b I draft
  6:29446d2dc5419c5f97447a8bc062e4cc328bf241 G draft
  9:dec04b246d7cbb670c6689806c05ad17c835284e J secret

  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
  $ cat hg.pid > $DAEMON_PIDS

All non-secret heads returned by default

  $ sendhttpv2peer << EOF
  > command heads
  > EOF
  creating http peer for wire protocol version 2
  sending heads command
  response: [
    b'\x1dok\x91\xd4J\xab\xa6\xd5\xe5\x80\xbc0\xa9\x94\x850\xdb\xe0\x0b',
    b'\xaeI.6\xb0\xc83\x9f\xfa\xf3(\xd0\x0b\x85\xb4R]\xe1\x16^',
    b')Dm-\xc5A\x9c_\x97Dz\x8b\xc0b\xe4\xcc2\x8b\xf2A'
  ]

Requesting just the public heads works

  $ sendhttpv2peer << EOF
  > command heads
  >     publiconly 1
  > EOF
  creating http peer for wire protocol version 2
  sending heads command
  response: [
    b'x\xd2\xdc\xa46\xb2\xf5\xb1\x88\xac&~)\xb8\x1e\x07&m8\xfc'
  ]

  $ cat error.log