Comment # 2 on bug 937765 from Freek de Kruijf

I tried exactly the same files in /etc/sysconfig/network/ and with the same USB
dongle as on my RPi1B on my RPi2B. On the RPi2B the network behaves as it
should. I can ifup wlan0 and get access via ssh, even after ifdown eth0. I also
see the proper MAC addresses in the ARP table on my desktop.
After removing the file ifcfg-eth0 and a reboot, the wlan0 interface comes up
and I have access via that interface.
So the problem seems to be only related to the RPi1.