Await in catch block

I have the following code:

WebClient wc = new WebClient();
string result;
try
{
  result = await wc.DownloadStringTaskAsync( new Uri( "http://badurl" ) );
}
catch
{
  result = await wc.DownloadStringTaskAsync( new Uri( "http://fallbackurl" ) );
}

Basically I want to download from a URL and when it fails with an exception I want to download from another URL. Both time async of course. However the code does not compile, because of

error CS1985: Cannot await in the body of a catch clause

OK, it's forbidden for whatever reason but what's the correct code pattern here?

EDIT:

The good news is that C# 6.0 will likely allow await calls both in catch and finally blocks.