Fix case where getfqdn() returns the ipv4 address.
Fix case where getfqdn() returns the ipv4 address.

Ask for the self-assigned hostname in this case, since this is more useful than
the IP address.

R=csharp@chromium.org
BUG=

Review URL: https://codereview.appspot.com/116860043

madecoste/swarming,madecoste/swarming,luci/luci-py,pombreda/swarming,pombreda/swarming,madecoste/swarming,luci/luci-py,pombreda/swarming,luci/luci-py,pombreda/swarming,madecoste/swarming,luci/luci-py