tests/test-narrow-acl.t

tests: add a module that can perform the equivalent of `SIGKILL` on any OS

I started with this being Windows specific, but let's push all of the decision
making into this function so that it can just be called by the tests.  The
tradeoff is that this is very specific to sending `SIGKILL`- since
`signal.SIGKILL` doesn't exist on Windows, the desired signal can't be passed
from the caller.  Maybe there's a way, but let's wait until there's a need.

We don't use `killdaemons.py` unconditionally because it starts with a more
graceful `SIGTERM` on posix.

Make a narrow clone then archive it
  $ . "$TESTDIR/narrow-library.sh"

  $ hg init master
  $ cd master

  $ for x in `$TESTDIR/seq.py 3`; do
  >   echo $x > "f$x"
  >   hg add "f$x"
  >   hg commit -m "Add $x"
  > done
  $ cat >> .hg/hgrc << EOF
  > [narrowacl]
  > default.includes=f1 f2
  > EOF
  $ hg serve -a localhost -p $HGPORT1 -d --pid-file=hg.pid
  $ cat hg.pid >> "$DAEMON_PIDS"

  $ cd ..
  $ hg clone http://localhost:$HGPORT1 narrowclone1
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets * (glob)
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

The clone directory should only contain f1 and f2
  $ ls -A -1 narrowclone1 | sort
  .hg
  f1
  f2

Requirements should contain narrowhg
  $ hg debugrequires -R narrowclone1 | grep narrowhg
  narrowhg-experimental

NarrowHG should track f1 and f2
  $ hg -R narrowclone1 tracked
  I path:f1
  I path:f2

Narrow should not be able to widen to include f3
  $ hg -R narrowclone1 tracked --addinclude f3
  comparing with http://localhost:$HGPORT1/
  searching for changes
  abort: The following includes are not accessible for test: ['path:f3']
  [255]
  $ ls -A -1 narrowclone1 | sort
  .hg
  f1
  f2
  $ hg -R narrowclone1 tracked
  I path:f1
  I path:f2

Narrow should allow widen to include f2
  $ hg -R narrowclone1 tracked --removeinclude f2 > /dev/null
  $ hg -R narrowclone1 tracked
  I path:f1
  $ ls -A -1 narrowclone1 | sort
  .hg
  f1
  $ hg -R narrowclone1 tracked --addinclude f2
  comparing with http://localhost:$HGPORT1/
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 0 changesets with 1 changes to 1 files
  $ hg -R narrowclone1 tracked
  I path:f1
  I path:f2
  $ ls -A -1 narrowclone1 | sort
  .hg
  f1
  f2