BUG: Didn't modify route table when change interface's second address

Hi,

The bug came out by this:
1.ifconfig eth0:1 192.168.0.1
2.route add default gw 192.168.0.1
3.ifconfig eth0:1 172.168.0.1
4.route table is:
Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         192.168.0.1     0.0.0.0         UG    0      0        0 eth0
default         128.5.130.254   0.0.0.0         UG    0      0        0 eth0
loopback        *               255.0.0.0       U     0      0        0 lo
128.5.130.0     *               255.255.255.0   U     0      0        0 eth0
link-local      *               255.255.0.0     U     0      0        0 eth0
172.168.0.0     *               255.255.0.0     U     0      0        0 eth0

Notice that,192.168.0.1 should be deleted because eth0:1's IP had been changed.

This bug seems to be long time exist.I test on kernel version 2.6.32 and 3.0.13,they both have the question.

https://bugzilla.kernel.org/show_bug.cgi?id=67171