PT-42880563:  When timer C fires and an INVITE transaction is already within or beyond the COMPLETED state, touch() method is still invoked.  This results to the transaction lifetime getting reset.  The current lifetime is 5 minutes.  having timer C reset this doubles the transaction lifetime to 10 minutes.   This can be normally interpreted as leak.  However, this is just a case of delayed garbage collection.  This patch corrects this from ever occuring.