tests/test-empty-dir.t

identify: only query remote bookmarks if needed

Instead of all the time when operating on a remote repo. This
perf regression was introduced in 15a79ac823e8, in 4.3.

This datahint method returns nothing for -Tjson, -Tpickle, -Tdebug
--config ui.formatdebug=true and --config ui.formatjson, so the
bookmarks won't show up. I don't know what these formatters are for.
plainformatter and templateformatter work properly, and the few other
uses of datahint should have the same kind of problem.

There is further weirdness where "--template '{node}'" is not enough
to avoid querying the bookmarks, you also need to pass --id or -q.

Differential Revision: https://phab.mercurial-scm.org/D4819

  $ hg init

  $ echo 123 > a
  $ hg add a
  $ hg commit -m "first" a

  $ mkdir sub
  $ echo 321 > sub/b
  $ hg add sub/b
  $ hg commit -m "second" sub/b

  $ cat sub/b
  321

  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cat sub/b 2>/dev/null || echo "sub/b not present"
  sub/b not present

  $ test -d sub || echo "sub not present"
  sub not present