(Do not use ``git checkout`` to view a content of a file in a commit,
use ``git cat-file -p``; e.g. ``git cat-file -p HEAD~:path/to/README``).
-TODO: describe undo strategies: git reset, git revert,
-git reflog. "Commit early, commit often".
+TODO: describe undo strategies: git reset, git reflog, git revert.
+"Commit early, commit often".
How to undo a merge
https://www.kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html