stylelint: selector-pseudo-colon-no-invalid-space

Describe the issue. Is it a bug or a feature request (new rule, new option, etc.)?

Valid:

a:hover {
  color: red;
}

a
:hover {
  color: red !important;
}

With one options: “never”

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After looking through the specs more closely, I’ve a few misgivings about this rule now.

“pseudo” isn’t really a thing. There are pseudo-classes and pseudo-elements, but not “pseudos”. We’ve only targeted the latter two elsewhere.
I’m not entirely convinced we’re right about where space is valid or invalid. There’s a lot going on in this spec.

As such, I’m in favour of pushing this group of rules to experimental plugins.