Fixed [""] for /route/ on CaptureAll apis.

* Routes ending in a `CaptureAll` now get an empty list instead of
    [""] when they have a trailing slash.
  * WARNING: I think this will break the expectation that a rooted
    capture all will produce [""] for `//`.  That is, previously `// =>
    [""]`, but I think `// => []`.  I will make some tests to check
    and see what is going on with this.

servant-server/src/Servant/Server/Internal/Router.hs

@@ -178,7 +178,14 @@ runRouterEnv fmt router env request respond  =
           -> let request' = request { pathInfo = rest }
              in  runRouterEnv fmt router' (first, env) request' respond
     CaptureAllRouter router' ->
-      let segments = pathInfo request
+      let segments = case pathInfo request of
+            -- This case handles empty capture alls in a sub route like:
+            -- /legs/ => [] instead of [""]
+            -- But will this break a rooted capture all? like:
+            -- // => [] instead of [""]
+            -- Maybe we should fix it in Wai first.
+            [""] -> []
+            xs -> xs
           request' = request { pathInfo = [] }
       in runRouterEnv fmt router' (segments, env) request' respond
     RawRouter app ->

servant-server/test/Servant/ServerSpec.hs

@@ -273,7 +273,7 @@ type CaptureAllApi =  "legs" :> CaptureAll "legs" Integer :> Get '[JSON] Animal
 captureAllApi :: Proxy CaptureAllApi
 captureAllApi = Proxy
 captureAllServer :: Server CaptureAllApi
-captureAllServer = handleLegs :<|> (return :: [String] -> Handler [String])
+captureAllServer = handleLegs :<|> return
   where
     handleLegs [] = return beholder
     handleLegs legs = case sum legs of