test_call: Fix race condition.
test_call: Fix race condition.

Change-Id: I30f4612f45bbf4c87548780301875179962811f4
Reviewed-on: http://gerrit.aldebaran.lan:8080/15260
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>

aldebaran/libqi,aldebaran/libqi-java,bsautron/libqi,aldebaran/libqi,vbarbaresi/libqi,aldebaran/libqi-java,aldebaran/libqi,aldebaran/libqi-java