Pair with spaces does not work (add failing scenarios)

I tried the following setup but didn't work.
```cl
(sp-with-modes 'sh-mode
  (sp-local-pair "[" "]" :actions nil)  ; I also tried '(:rem wrap insert)
  (sp-local-pair "[ " " ]")
  (sp-local-pair "[[" "]]"))
```

To replicate the problem, I wrote two failing scenarios.  I thought the problem was removing pairs but there was another problem with pair with whitespaces.

In case this takes sometime to fix, I propose to add `@known` tag so that you can keep travis result clean (e2f11e395860f6d51cadbfd1f0bbb0953195afa1).