tests/test-diffdir.t

largefiles: replace invocation of os.path module by vfs in lfutil.py

Replaces invocations os.path functions to methods in vfs. Unfortunately
(in my view) this makes code less readable, because instead of using
clear variable names with path it needs to replace them with vfs(..).
I need guidance how to make such transition look more readable.

For example in this patch there is example with few places with
wvfs.join(standindir), standindir before this patch was absolute
path, in this it is changed to relative because it is used also
in expression wvfs.join(standindir, pat).

  $ hg init
  $ touch a
  $ hg add a
  $ hg ci -m "a"

  $ echo 123 > b
  $ hg add b
  $ hg diff --nodates
  diff -r 3903775176ed b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +123

  $ hg diff --nodates -r tip
  diff -r 3903775176ed b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +123

  $ echo foo > a
  $ hg diff --nodates
  diff -r 3903775176ed a
  --- a/a
  +++ b/a
  @@ -0,0 +1,1 @@
  +foo
  diff -r 3903775176ed b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +123

  $ hg diff -r ""
  hg: parse error: empty query
  [255]
  $ hg diff -r tip -r ""
  hg: parse error: empty query
  [255]

Remove a file that was added via merge. Since the file is not in parent 1,
it should not be in the diff.

  $ hg ci -m 'a=foo' a
  $ hg co -Cq null
  $ echo 123 > b
  $ hg add b
  $ hg ci -m "b"
  created new head
  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg rm -f a
  $ hg diff --nodates

Rename a file that was added via merge. Since the rename source is not in
parent 1, the diff should be relative to /dev/null

  $ hg co -Cq 2
  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg mv a a2
  $ hg diff --nodates
  diff -r cf44b38435e5 a2
  --- /dev/null
  +++ b/a2
  @@ -0,0 +1,1 @@
  +foo
  $ hg diff --nodates --git
  diff --git a/a2 b/a2
  new file mode 100644
  --- /dev/null
  +++ b/a2
  @@ -0,0 +1,1 @@
  +foo