remove redundant case covered by mapValVal in substitution code
remove redundant case covered by mapValVal in substitution code

darcs-hash:20070608035715-1a7c6-260291cbd2c5da36a3e702b64d02214e49b9c32d

kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc