tests/test-context-metadata.t

fsmonitor: use nonnormalset from dirstatemap

`dirstate._nonnormalset` has been moved to `dirstate._map.nonnormalset` by
60927b19ed65 (dirstate: move nonnormal and otherparent sets to dirstatemap)
and is guaranteed to be existed.

Let's update fsmonitor code to use the new `nonnormalset`. Thix fixed a perf
regression that slows down `hg status` by 0.5 seconds in one of our
production repos.

Differential Revision: https://phab.mercurial-scm.org/D1184

Tests about metadataonlyctx

  $ hg init
  $ echo A > A
  $ hg commit -A A -m 'Add A'
  $ echo B > B
  $ hg commit -A B -m 'Add B'
  $ hg rm A
  $ echo C > C
  $ echo B2 > B
  $ hg add C -q
  $ hg commit -m 'Remove A'

  $ cat > metaedit.py <<EOF
  > from __future__ import absolute_import
  > from mercurial import context, registrar
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command('metaedit')
  > def metaedit(ui, repo, arg):
  >     # Modify commit message to "FOO"
  >     with repo.wlock(), repo.lock(), repo.transaction('metaedit'):
  >         old = repo['.']
  >         kwargs = dict(s.split('=', 1) for s in arg.split(';'))
  >         if 'parents' in kwargs:
  >             kwargs['parents'] = kwargs['parents'].split(',')
  >         new = context.metadataonlyctx(repo, old, **kwargs)
  >         new.commit()
  > EOF
  $ hg --config extensions.metaedit=$TESTTMP/metaedit.py metaedit 'text=Changed'
  $ hg log -r tip
  changeset:   3:ad83e9e00ec9
  tag:         tip
  parent:      1:3afb7afe6632
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Changed
  
  $ hg --config extensions.metaedit=$TESTTMP/metaedit.py metaedit 'parents=0' 2>&1 | egrep '^RuntimeError'
  RuntimeError: can't reuse the manifest: its p1 doesn't match the new ctx p1

  $ hg --config extensions.metaedit=$TESTTMP/metaedit.py metaedit 'user=foo <[e-mail]>'
  $ hg log -r tip
  changeset:   4:1f86eaeca92b
  tag:         tip
  parent:      1:3afb7afe6632
  user:        foo <[e-mail]>
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Remove A