ref: 38e525fb7b8562a96422ffe9d7c65cb3569b3e6b
dir: /bugs-fixed/space.ok/
" " ~ [[:blank:]] " " ~ [[:space:]] \a !~ [[:blank:]] \a !~ [[:space:]] \b !~ [[:blank:]] \b !~ [[:space:]] \f !~ [[:blank:]] \f ~ [[:space:]] \n !~ [[:blank:]] \n ~ [[:space:]] \r !~ [[:blank:]] \r ~ [[:space:]] \t ~ [[:blank:]] \t ~ [[:space:]] \v !~ [[:blank:]] \v ~ [[:space:]]