Repro for git-lfs rebase issue

git-lfs fails to checkout new lfs objects after rebasing commits in which lfs objects were added.

Before repro'ing, it may be helpful to observe that:

• the test branch has two commits not on the master branch:
  • one that starts tracking png files with lfs
  • one that actually adds a png file as an lfs object
• the master branch has one commit not on the test branch

Repro steps:

1. checkout the test branch
2. observe that oops.png is properly checked out:
   • run git lfs ls-files, which indicates * full object
   • run file oops.png, the result is an image
3. rebase the test branch onto the master branch
4. observe that oops.png is not properly checked out:
   • run git lfs ls-files, which incidates - LFS pointer
   • run file oops.png, the result is an ASCII text file