Strand.process: fix race #31143
Strand.process: fix race #31143

When restarting process because of pending work, the next iteration may start
before we reset the thread id. The consequence is that isInThisContext will
always return false.

Change-Id: Ib2307f4a96f80a3a7b0be97316cc874246197c08
Reviewed-on: http://gerrit.aldebaran.lan/59719
Reviewed-by: pdaouadi <fc1eb3334d3fdad315bae23aa166bc70bd434067@aldebaran-robotics.com>
Tested-by: pdaouadi <fc1eb3334d3fdad315bae23aa166bc70bd434067@aldebaran-robotics.com>
(cherry picked from commit 8f9034fcf5d5bffea75cdfe7f07aaeeffe4e1597)

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi