Merge branch 'jk/filter-branch-come-back-to-original'

When used with "-d temporary-directory" option, "git filter-branch"
failed to come back to the original working tree to perform the
final clean-up procedure.

* jk/filter-branch-come-back-to-original:
  filter-branch: return to original dir after filtering

diff --cc git-filter-branch.sh
Simple merge

diff --cc t/t7003-filter-branch.sh
Simple merge