URI encoding breaks linking to text fragments

[dchacke]

Redcarpet seems to automatically URI encode the href for links. That’s fine in most cases except when linking to text fragments, where the tilde must not be encoded.

Current behavior:

'[foo](https://example.com#:~:text=bar)'
# => href: 'https://example.com#:%7E:text=bar'
#                                 ^

Expected behavior:

'[foo](https://example.com#:~:text=bar)'
# => href: 'https://example.com#:~:text=bar'
#                                ^

As a workaround, I use a heuristic for post processing:

def postprocess text
  text.gsub('#:%7E:text=', '#:~:text=')
end