Set PYTHONPATH for old control loops

Running them doesn't get you the right files (namespace issues at
least), but at least they kind of work.

Change-Id: I69faa943d4db14c29bdaa6abb035f6f34ca5244d
diff --git a/y2014/control_loops/update_polydrivetrain.sh b/y2014/control_loops/update_polydrivetrain.sh
index 2e2748e..2b559c6 100755
--- a/y2014/control_loops/update_polydrivetrain.sh
+++ b/y2014/control_loops/update_polydrivetrain.sh
@@ -2,6 +2,8 @@
 #
 # Updates the polydrivetrain controllers (for both robots) and CIM models.
 
+export PYTHONPATH=../../frc971/control_loops/python
+
 cd $(dirname $0)
 
 ./python/polydrivetrain.py drivetrain/polydrivetrain_dog_motor_plant.h \