tests/test-debugindexdot.t

resourceutil: force filesystem access to resources when using py2exe

I don't know why it doesn't work, but it avoids this fatal error on startup:

    > hg debugshell
    Traceback (most recent call last):
      File "hg", line 58, in <module>
      File "mercurial\dispatch.pyc", line 143, in run
      File "mercurial\dispatch.pyc", line 232, in dispatch
      File "mercurial\dispatch.pyc", line 254, in _rundispatch
      File "mercurial\ui.pyc", line 316, in load
      File "mercurial\rcutil.pyc", line 98, in rccomponents
      File "mercurial\rcutil.pyc", line 68, in default_rc_resources
      File "mercurial\utils\resourceutil.pyc", line 102, in contents
      File "<frozen zipimport>", line 775, in contents
    AssertionError

I assume the py2 version of py2exe never hit this because `importlib.resources`
failed to import.

Differential Revision: https://phab.mercurial-scm.org/D12554

Just exercise debugindexdot
Create a short file history including a merge.
  $ hg init t
  $ cd t
  $ echo a > a
  $ hg ci -qAm t1 -d '0 0'
  $ echo a >> a
  $ hg ci -m t2 -d '1 0'
  $ hg up -qC 0
  $ echo b >> a
  $ hg ci -m t3 -d '2 0'
  created new head
  $ HGMERGE=true hg merge -q
  $ hg ci -m merge -d '3 0'

  $ hg debugindexdot -c
  digraph G {
  	-1 -> 0
  	0 -> 1
  	0 -> 2
  	2 -> 3
  	1 -> 3
  }

  $ hg debugindexdot -m
  digraph G {
  	-1 -> 0
  	0 -> 1
  	0 -> 2
  	2 -> 3
  	1 -> 3
  }

  $ hg debugindexdot a
  digraph G {
  	-1 -> 0
  	0 -> 1
  	0 -> 2
  	2 -> 3
  	1 -> 3
  }

  $ cd ..