vsc.utils.run.Command.run should poll() the process for its timeout

[piojo-zz]

For timeouts, vsc.util.run.Command.run() checks for the existence of /proc/<pid> for validating the timeout.

This is unreliable: proc may not be mounted (under a chroot or with init=/bin/sh) or who knows what else.

The Pythonic way to check for process termination is to call poll():

p = Popen(["my", "command"])
while p.poll() is None:
   pass
p.terminate() # or p.kill()

Also, commands shouldn't run in subshells by default.