title: Pydantic mangling input
body: <p>In the following example, I can't understand why pydantic is mangling the type input.</p>
  <pre class="lang-py prettyprint-override"><code>from pydantic import BaseModel
  from typing import Union, List
  
  
  class Foo(BaseModel):
      bar: Union[str, dict, List[dict]]
  
  f = Foo(bar=[{'foo': 'bar', 'stuff': 'things'}])
  assert f.bar == {'foo': 'stuff'}
  </code></pre>
  <p>Why is the type changing from a list to a dict and further mangling the keys into a key value pair? Don't know if this is pydantic specific or just typing issues.</p>
  <p>And as a followup, what can I do to fix this so that the types aren't mangled.</p>