asyncio, tulip issue 190: Process.communicate() must ignore BrokenPipeError

If you want to handle the BrokenPipeError, you can easily reimplement
communicate().

Add also a unit test to ensure that stdin.write() + stdin.drain() raises
BrokenPipeError.
(Merge 3.4) asyncio, tulip issue 190: Process.communicate() must ignore
BrokenPipeError

If you want to handle the BrokenPipeError, you can easily reimplement
communicate().

Add also a unit test to ensure that stdin.write() + stdin.drain() raises
BrokenPipeError.
asyncio, tulip issue 190: Process.communicate() now ignores
ConnectionResetError too
(Merge 3.4) asyncio, tulip issue 190: Process.communicate() now ignores
ConnectionResetError too