wg-quick up (on linux) fails in case of several default routes

[Chris]

In case there is more than one default route (with different metrics):
wg-quick tries to set the route to the wg server through the default gateway.
However, in case there is more than one default route it
fails setting the route to server correctly.

Instead it should run through the list of default gateways and set routes to the
wg server through ALL default gateways with a metric of the corresponding 
default route.
Chris

P.S.: Shall one report bugs here or rather at gitlab or both?