tests/test-wireproto-command-listkeys.t

files: speed up `hg files` when no flags change display

It's not the first time I see slowness from this command slow down
tools built on top of hg.

The majority of the time is spent merely printing the result before
this change, which is clearly not how it should be (especially since
the computation of the result also looks slow).

Running `hg files` in mozilla-central:

parent revision: 1,260s
this commit: 0,683s
this commit without batching ui.write: 0,931s
this commit replacing the body of the loop with `pass`: 0,566s

This looks like a prime candidate for a rust fast path, but until
then, it seems reasonable to optimize the python.

Differential Revision: https://phab.mercurial-scm.org/D8586

  $ . $TESTDIR/wireprotohelpers.sh

  $ hg init server
  $ enablehttpv2 server
  $ cd server
  $ hg debugdrawdag << EOF
  > C D
  > |/
  > B
  > |
  > A
  > EOF

  $ hg phase --public -r C
  $ hg book -r C @

  $ hg log -T '{rev}:{node} {desc}\n'
  3:be0ef73c17ade3fc89dc41701eb9fc3a91b58282 D
  2:26805aba1e600a82e93661149f2313866a221a7b C
  1:112478962961147124edd43549aedd1a335e44bf B
  0:426bada5c67598ca65036d57d9e4b64b0c1ce7a0 A

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

Request for namespaces works

  $ sendhttpv2peer << EOF
  > command listkeys
  >     namespace namespaces
  > EOF
  creating http peer for wire protocol version 2
  sending listkeys command
  response: {
    b'bookmarks': b'',
    b'namespaces': b'',
    b'phases': b''
  }

Request for phases works

  $ sendhttpv2peer << EOF
  > command listkeys
  >     namespace phases
  > EOF
  creating http peer for wire protocol version 2
  sending listkeys command
  response: {
    b'be0ef73c17ade3fc89dc41701eb9fc3a91b58282': b'1',
    b'publishing': b'True'
  }

Request for bookmarks works

  $ sendhttpv2peer << EOF
  > command listkeys
  >     namespace bookmarks
  > EOF
  creating http peer for wire protocol version 2
  sending listkeys command
  response: {
    b'@': b'26805aba1e600a82e93661149f2313866a221a7b'
  }

  $ cat error.log