if !mod_is_left {

                // If this split isn't at the root, and the page
                // modified in the last step is the one on the left of
                // the entry, move back one step before inserting the
                // split key/value.
                //
                // (remember that we popped the stack upon entering
                // this function).
                if cursor.len() > 0 && !mod_is_left {