Add comments about the IPAddr hack

app/models/screened_ip_address.rb

@@ -14,9 +14,9 @@ class ScreenedIpAddress < ActiveRecord::Base
     match_for_ip_address(ip_address) || create(opts.slice(:action_type).merge(ip_address: ip_address))
   end
 
-  # @Neil please review, in rails 4 when setting an ip address attribute a conversion takes place
-  #  this may explode meaning you will never even reach the validator
-  # We can work around the issue like so, but I wonder if the spec is valid
+  # In Rails 4.0.0, validators are run to handle invalid assignments to inet columns (as they should).
+  # In Rails 4.0.1, an exception is raised before validation happens, so we need this hack for
+  # inet/cidr columns:
   def ip_address=(val)
     write_attribute(:ip_address, val)
   rescue IPAddr::InvalidAddressError

lib/validators/ip_address_format_validator.rb

@@ -4,8 +4,15 @@ class IpAddressFormatValidator < ActiveModel::EachValidator
 
   def validate_each(record, attribute, value)
     if rails4?
-      # In Rails 4, ip_address will be nil if an invalid IP address was assigned.
+      # In Rails 4.0.0, ip_address will be nil if an invalid IP address was assigned.
       # https://github.com/jetthoughts/rails/commit/0aa95a71b04f2893921c58a7c1d9fca60dbdcbc2
+
+      # BUT: in Rails 4.0.1, validators don't get a chance to
+      # run before IPAddr::InvalidAddressError is raised.
+      # I don't see what broke it in rails 4.0.1...
+      # So this validator doesn't actually do anything anymore.
+      # But let's keep it in case a future version of rails fixes the problem and allows
+      # validators to work on inet and cidr columns.
       if record.ip_address.nil?
         record.errors.add(attribute, :invalid)
       end