bunpen: refactor: dbus: use path::abs in place of strings::hasprefix

pkgs/by-name/bunpen/restrict/dbus_proxy.ha

@@ -165,9 +165,8 @@ fn parse_dbus_address(address: (str | void)) (path::buffer | path::error) = {
         return path::not_prefix;
       };
       value = strings::sub(value, len(expected_prefix));
-      if (!strings::hasprefix(value, "/")) {
+      if (!path::abs(value)) {
         // expect the dbus bus address to be an absolute path
-        // TODO: consider parsing this as an actual path?
         return path::not_prefix;
       };
       yield path::init(value);