tests/test-nested-repo.t

tests: make chunk header of external diff glob-ed for portability

Before this patch, some tests using external "diff" command via
extdiff extension fail on Solaris, because system standard "diff" (=
/usr/bin/diff) on Solaris always formats chunk header in the style
below:

  @@ -X.x +Y.y @@

even though "diff" on Linux sometimes omits ".x" and/or ".y" in it.

This patch makes chunk header of external diff glob-ed for portability
of tests, and adds check-code.py rules to detect such diff output in
tests.

This patch also changes "hg diff" output in test-subrepo-git to
simplify detection rules, even though it is certainly portable because
these lines are generated by "git" command.

This patch is a part of making tests using external "diff" portable,
and tests below aren't yet portable even after this patch.

  test-largefiles-update.t
  test-subrepo-deep-nested-change.t

  $ hg init a
  $ cd a
  $ hg init b
  $ echo x > b/x

Should print nothing:

  $ hg add b
  $ hg st

  $ echo y > b/y
  $ hg st

Should fail:

  $ hg st b/x
  abort: path 'b/x' is inside nested repo 'b' (glob)
  [255]
  $ hg add b/x
  abort: path 'b/x' is inside nested repo 'b' (glob)
  [255]

Should fail:

  $ hg add b b/x
  abort: path 'b/x' is inside nested repo 'b' (glob)
  [255]
  $ hg st

Should arguably print nothing:

  $ hg st b

  $ echo a > a
  $ hg ci -Ama a

Should fail:

  $ hg mv a b
  abort: path 'b/a' is inside nested repo 'b' (glob)
  [255]
  $ hg st

  $ cd ..