swagger 2.0 upload causing "base_url must not end with a '/'"

[benjamine]

when uploading a swagger 2.0 json,
with this structure:

{
  "swagger": "2.0",
  "host": "api.example.io",
  "schemes": [
    "https"
  ],
  "basePath": "/",
  ...

upload fails with: base_url[https://api.example.io/] must not end with a '/'
although this is valid swagger 2.0. (and an empty basePath is invalid swagger 2.0)