title: Invalid redirect_uri even though they are the same
body: <p>When trying to login to identityserver (using .net core 3 preview) I get Invalid redirect_uri error even though the request uri and the allowed one are identical.</p>
  
  <p>What else could I be doing wrong?</p>
  
  <pre class="lang-cs prettyprint-override"><code>fail: IdentityServer4.Validation.AuthorizeRequestValidator[0]
        Invalid redirect_uri: http://localhost:1337/authentication/login-callback
  {
          "ClientId": "myapp",
          "ClientName": "myapp",
          "AllowedRedirectUris": [
            "http://localhost:1337/authentication/login-callback"
          ],
          "SubjectId": "anonymous",
          "RequestedScopes": "",
          "Raw": {
            "client_id": "myapp",
            "redirect_uri": "http://localhost:1337/authentication/login-callback",
            "response_type": "id_token token",
            "scope": "webAPI openid profile",
            "state": "5a10fc5a7006475c8d3a348c711ca58a",
            "nonce": "ae6f9f35837241e1ba3841c2ff8a4fce",
            "prompt": "none"
          }
        }
  fail: IdentityServer4.Endpoints.AuthorizeEndpoint[0]
        Request validation failed
  </code></pre>