When, after an event, measures are taken which, if taken previously,
would have made the event less likely to occur, evidence of the
subsequent measures is not admissible to prove negligence or culpable
conduct in connection with the event. This rule does not require the
exclusion of evidence of subsequent measures when offered for another
purpose, such as proving ownership, control, or feasibility of
precautionary measures, if controverted, or impeachment.