proview: fix pgrep exit code mistake

component/proviewR/buildout.cfg

@@ -380,7 +380,7 @@ pre-build =
   ${xserver:location}/bin/Xorg -noreset +extension GLX +extension RANDR +extension RENDER -config ${:compile-dir}/src/tools/dummy_display/xorg.conf :99 &
 
 post-install =
-  PID=`pgrep -u "$(whoami)" -f -x  '${xserver:location}/bin/Xorg.*'`
+  PID=`pgrep -u "$(whoami)" -f -x  '${xserver:location}/bin/Xorg.*'` || true #pgrep returns 1 on notfound
   if [ ! -z "$PID" ]; then kill -TERM $PID; fi
 
 make-targets =