As PID file is created by daemon, it might happen that although the
return code is 0, the PID file does not exist yet. And afterwards,
communicate() call might hang for some reason. As there is no way to
put timeout on communicate call in python2, and in order to make
this change more backportable, this patch uses non-blocking read to
get the values of stdout and stderr of the call.
Story: 2006514
Task: 36511
Change-Id: I0bf38321b0135ea17439d35081b5727fd4d827c8
efc2d5fcd3