Call with existing python interpreter.

Supports cases when operating system does not provide /usr/bin/python which is
hardcoded in genbt5list.

software/sanef/software.cfg

@@ -60,7 +60,7 @@ update-command = ${:command}
 recipe = plone.recipe.command
 stop-on-error = true
 command =
-  ${erp5:location}/product/ERP5/bin/genbt5list ${erp5:location}/product/ERP5/bootstrap ${erp5:location}/bt5 ${bt5-bef:location}
+  ${buildout:executable} ${erp5:location}/product/ERP5/bin/genbt5list ${erp5:location}/product/ERP5/bootstrap ${erp5:location}/bt5 ${bt5-bef:location}
 update-command = ${:command}