kern/54781: Specifying the default gateway fails with "network is unreachable"

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>Number:         54781
>Category:       kern
>Synopsis:       Specifying the default gateway fails with "network is unreachable"
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Dec 18 13:15:00 +0000 2019
>Originator:     qweo
>Release:        9.0-RC1
>Organization:
>Environment:
>Description:
Specifying the default gateway would fail with "network is unreachable" on evbmips (10" Lemote Yeeloong), making network install impossible.
>How-To-Repeat:
route add default <IP>, or the sysinst equivalent.
>Fix: