tests/test-diffdir.t

revlog.revision(): minor cleanup

Rename some variables, making the name more obvious (in particular "cache" was
actually two different variable.
Move code around, moving the index preloading before the deltachain computation,
without that index preloading was useless (everything was read in deltachain).

  $ hg init
  $ touch a
  $ hg add a
  $ hg ci -m "a" -d "1000000 0"

  $ echo 123 > b
  $ hg add b
  $ hg diff --nodates
  diff -r acd8075edac9 b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +123

  $ hg diff --nodates -r tip
  diff -r acd8075edac9 b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +123

  $ echo foo > a
  $ hg diff --nodates
  diff -r acd8075edac9 a
  --- a/a
  +++ b/a
  @@ -0,0 +1,1 @@
  +foo
  diff -r acd8075edac9 b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +123

  $ hg diff -r ""
  abort: 00changelog.i@: ambiguous identifier!
  $ hg diff -r tip -r ""
  abort: 00changelog.i@: ambiguous identifier!

  $ true