Comment # 2 on bug 1202658 from Marius Tomaschewski

Example showing the cause to apply the incomplete static settings
(while dhcp is in use and thus there is no static IPADDR):

# ip addr show dev dummy0
Device "dummy0" does not exist.
# ip link add dev dummy0 type dummy

# ip link set up dummy0
# ip addr show dev dummy0
55: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
group default qlen 1000
    link/ether ce:0e:42:76:18:82 brd ff:ff:ff:ff:ff:ff
# ip route show dev dummy0
# ip route add 10.2.1.1/32 via 10.1.1.252 dev dummy0
Error: Nexthop has invalid gateway.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

-> The kernel rejects to create the route with gateway.

After prepending a direct route allowing to reach the gateway:

# ip route add 10.1.1.252 dev dummy0
# ip route add 10.2.1.1/32 via 10.1.1.252 dev dummy0

-> both routes are applied:

# ip addr show dev dummy0
55: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
group default qlen 1000
    link/ether ce:0e:42:76:18:82 brd ff:ff:ff:ff:ff:ff
# ip route show dev dummy0
10.1.1.252 scope link 
10.2.1.1 via 10.1.1.252