Usually the command automatically creates a commit with a
commit log message stating which commit was reverted. This flag
applies the change necessary to revert the named commit to your
working tree, but does not make the commit. In addition, when this
option is used, your working tree does not have to match the HEAD
commit. The revert is done against the beginning state of your
working tree.
This is useful when reverting more than one commits' effect to
your working tree in a row.