tests/test-issue433.t

subrepo: fix subrelpath for git subrepos

This patch conforms gitsubrepo code to the variable naming scheme of the other
subrepo implementations. All user-facing path references should be relative
to the root repository.

http://mercurial.selenic.com/bts/issue433

  $ hg init
  $ echo a > a
  $ hg commit -Ama
  adding a

  $ hg parents -r 0 doesnotexist
  abort: 'doesnotexist' not found in manifest!
  [255]