Python issue #23475: Fix test_close_kill_running()
Python issue #23475: Fix test_close_kill_running()

Really kill the child process, don't mock completly the Popen.kill() method.

This change fix memory leaks and reference leaks.

Martiusweb/asyncio,haypo/trollius,haypo/trollius,jashandeep-sohi/asyncio,ajdavis/asyncio,gvanrossum/asyncio,1st1/asyncio,manipopopo/asyncio,gvanrossum/asyncio,fallen/asyncio,manipopopo/asyncio,vxgmichel/asyncio,ajdavis/asyncio,ajdavis/asyncio,jashandeep-sohi/asyncio,Martiusweb/asyncio,vxgmichel/asyncio,fallen/asyncio,vxgmichel/asyncio,jashandeep-sohi/asyncio,haypo/trollius,Martiusweb/asyncio,1st1/asyncio,gvanrossum/asyncio,gsb-eng/asyncio,manipopopo/asyncio,1st1/asyncio,gsb-eng/asyncio,gsb-eng/asyncio,fallen/asyncio