Log Message:
www/hs-servant-server: update to servant-server-0.20.2

0.20.2
----

- Fix build of examples/greet.hs. Add "429 Too Many Requests" error. \ 
[#1591](https://github.com/haskell-servant/servant/pull/1591)
- Full query string helpers \ 
[#1604](https://github.com/haskell-servant/servant/pull/1604)
  This involves a new instance `HasServer (QueryString :> api) context`.
- Add `MkHandler` pattern synonym \ 
[#1732](https://github.com/haskell-servant/servant/issues/1732) \ 
[#1733](https://github.com/haskell-servant/servant/pull/1733)

  Add a bidirectional pattern synonym to construct `Handler a` values from `IO
  (Either ServerError a)` ones, and match in the other direction.
- Add instance `HasServer (EmptyAPI :> api) context` \ 
[#1775](https://github.com/haskell-servant/servant/pull/1775)
- Bugfix - CaptureAll produces [""] for empty paths due to trailing \ 
slash. [#1243](https://github.com/haskell-servant/servant/issues/1243) \ 
[#1516](https://github.com/haskell-servant/servant/pull/1516)

  CaptureAll resulted in `[""]` for empty paths due to trailing slash. \ 
 Similar
  oddities occurred around these edge cases like `"/"` resulted in \ 
`[]` correctly,
  but `"//"` resulted in `["", ""]`.  This patch \ 
simply eliminates the first `""`
  in the pathinfo list as taken from the wai response.  This might break user
  code that relies on personal shims to solve the problem, however simply \ 
removing their
  workarounds should fix their code as the behavior is now sane.