We tell dhclient to name 121 option "classless-routes",
but in dhclient-script we parse classless_static_routes.
So either have to change the configuration or the script.
And since dhclient uses by default classless_static_routes,
let's change the configuration
-option classless-routes code 121 = array of unsigned integer 8;
+option classless-static-routes code 121 = array of unsigned integer 8;
request subnet-mask, broadcast-address, time-offset, routers,
domain-name, domain-name-servers, domain-search, host-name,
- root-path, interface-mtu, classless-routes;
+ root-path, interface-mtu, classless-static-routes;