According to proc man page process arguments in /proc/{pid}/cmdline
should be separated with '\0' char and that char was used in
neutron.agent.linux.utils.get_cmdline_from_pid function.
Recently in fullstack tests it was noticed that sometimes it may
happend that those arguments are separated with space char and this
caused failed test because async_process.AsyncProcess() was not able
to check that process is really active.
This patch adds attempt to split cmdline arguments with space in case
when split with '\0' returns only 1 element.
Change-Id: I35d4c0e2cf56fc3ff15cf307aaf11a8ad8489e1f
Closes-Bug: #1820870
(cherry picked from commit cf13b2f0cc)
93197576fa