Route scope not working properly for IPv6

[VladoLavor]

How to reproduce the bug using the example added in #1826
Make a copy of the resync method and name it resync2. In the copied method, replace the lines

LinuxRoute(routeResync()).
LinuxRoute(routeResyncIPv6()).

with

LinuxRoute(routeModified()).
LinuxRoute(routeModifiedIPv6()).

Add the following code at the end of AfterInit method (at line 129):

ctx, p.cancelResync = context.WithCancel(context.Background())
p.wg.Add(1)
go p.resync2(ctx, *timeout*4)

Then build and run the example.
The log of the last resync transaction contains the following:

  * executed operations (2021-11-30 17:24:49.56 +0100 CET -> 2021-11-30 17:24:49.58 +0100 CET, dur: 21ms):
      1. UPDATE:
          - key: config/linux/l3/v2/route/aaa1::/64/linux-tap2
          - prev-value: { outgoing_interface:"linux-tap2"  scope:GLOBAL  dst_network:"aaa1::/64"  metric:500 } 
          - new-value: { outgoing_interface:"linux-tap2"  scope:LINK  dst_network:"aaa1::/64"  metric:500 } 
      2. CREATE [PROPERTY WAS-MISSING]:
          - key: linux/link-local-route/linux-tap2/dest-address/aaa1::/64
          - value: <EMPTY> 

There should be no executed operations.
This shows that the LINK scope has not been properly configured or retrieved.

Investigate other scope options, including the site which should be IPv6 only.