LocalDispatcherTest : Work around Windows DLL problems

By importing Gaffer before GafferDispatch, we make sure the DLL paths
are set up in time. I suppose we could alternatively add the DLL paths
in every single Python module, but I don't have much appetite for that.

python/GafferDispatchTest/LocalDispatcherTest.py

@@ -1200,7 +1200,7 @@ def testShutdownDuringBackgroundDispatch( self ) :
 		# has finished.
 
 		output = subprocess.check_output(
-			[ str( Gaffer.executablePath() ), "env", "python", "-c", "import GafferDispatchTest; GafferDispatchTest.LocalDispatcherTest._shutdownDuringBackgroundDispatch()" ],
+			[ str( Gaffer.executablePath() ), "env", "python", "-c", "import Gaffer; import GafferDispatchTest; GafferDispatchTest.LocalDispatcherTest._shutdownDuringBackgroundDispatch()" ],
 			stderr = subprocess.STDOUT, text = True
 		)