Python issue #22685: Fix test_pause_reading() of test_subprocess
Python issue #22685: Fix test_pause_reading() of test_subprocess

* mock also resume_reading()
* ensure that resume_reading() is called

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