qbs config and qbs config ui do not show values for boolean variables and config-ui overwrites it with false

qbs config --list or qbs config var and qbs config-ui do not show values for boolean variables.
One sees always an empty string.
This has a very bad side effect especially in qbs config-ui:
opening it looking at a value, and then saving (without explicitly editing that value) tries to save an empty string, and thus convert it to false