gistfile1.txt

$ git status
# On branch master
nothing to commit, working directory clean
$ DYLD_INSERT_LIBRARIES=../../unco.dylib DYLD_FORCE_FLAT_NAMESPACE=YES git checkout HEAD^
Note: checking out 'HEAD^'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b new_branch_name

HEAD is now at 664f582... first commit
$ git status
# HEAD detached at 664f582
nothing to commit, working directory clean
$ ../../unco undo ~/.unco-log | sh -e
$ git status
# On branch master
nothing to commit, working directory clean
$