will this get docs building?

SConstruct

@@ -777,7 +777,7 @@ commandEnv["ENV"]["PYTHONPATH"] = commandEnv.subst( os.path.pathsep.join( [ "$BU
 # SIP on MacOS prevents DYLD_LIBRARY_PATH being passed down so we make sure
 # we also pass through to gaffer the other base vars it uses to populate paths
 # for third-party support.
-for v in ( 'ARNOLD_ROOT', 'DELIGHT_ROOT' ) :
+for v in ( 'ARNOLD_ROOT', 'DELIGHT_ROOT', 'ONNX_ROOT' ) :
 	commandEnv["ENV"][ v ] = commandEnv[ v ]
 
 def runCommand( command ) :