title: How to fix this: TypeError: expect a list of futures, not Task
body: <p>I'm trying to start a bunch of subprocess using asyncio.create_subprocess_exec:</p>
  
  <pre class="lang-py prettyprint-override"><code>procs = []
  for i in range(5):
      proc = await asyncio.create_subprocess_exec(...)
      procs.append(proc.wait())
      # doesn't work with this line either:
      procs.append(asyncio.create_task(proc.wait()))
  
  await asyncio.wait(*procs,..)
  # doesn't work with await asyncio.as_completed either. asyncio.gather do work, but I'd like to add timeout limit and return back to my code as earlier as possible.
  </code></pre>
  
  <p>the exception is:
  TypeError: expect a list of futures, not Task
  against line 'await asyncio.wait(*procs,..)
  The verion of Python is 3.8.</p>
  
  <p>Despite of be warned not to create future by myself in the official document, if there's a way to convert <em>proc</em> into Future, I'd like to try.</p>
  
  <p>Thanks!</p>