Gate scripts are trying to calculate the SUBNET_RANGE basing on IP address
of default interface. There is ipcalc tool used.
The issue is that based on infra datacenter selected to run the VM gate,
the default interface can have address with /32 network.
If IP has /32 network, the ipcalc would not calculate the network address,
for example 192.168.0.0/24, which is needed for ceph to be configured.
As a workaround, try to change the /32 to /24 after getting the IP of the
default interface, and then calculate the network address.
Change-Id: Ia2858c6a2b4c56fbc42ef06b5f157625a56beb3c
ece78c448d