Disallow invalid address prefixes in NSG rules in ARM portal
The ARM portal curently allows invalid address prefixes (e.g., 10.92.0.14/3) in NSG rules. The powershell cmdlet Set-AzureRmNetworkSecurityGroup does not. This is problematic for scripts which read in existing NSG rules, make a single valid modification, and then attempt to write the rules back out. It fails because the ARM portal allowed a bad entry.