Mono TypeConverter bug - always returns "true" for IsValid for int types

gistfile1.txt

[beep@pinky monotest]$ mono test.exe 12
Converting 12
Converted reported IsValid as True
Conversion successful 12
[beep@pinky monotest]$ mono test.exe fred
Converting fred
Converted reported IsValid as True
Conversion failed System.Exception: fred is not a valid value for Int32. ---> System.FormatException: Input string was not in the correct format
  at System.Int32.Parse (System.String s, NumberStyles style, IFormatProvider provider) [0x00000] in <filename unknown>:0
  at System.ComponentModel.Int32Converter.ConvertFromString (System.String value, System.Globalization.NumberFormatInfo format) [0x00000] in <filename unknown>:0
  at System.ComponentModel.BaseNumberConverter.ConvertFrom (ITypeDescriptorContext context, System.Globalization.CultureInfo culture, System.Object value) [0x00000] in <filename unknown>:0
  --- End of inner exception stack trace ---
  at System.ComponentModel.BaseNumberConverter.ConvertFrom (ITypeDescriptorContext context, System.Globalization.CultureInfo culture, System.Object value) [0x00000] in <filename unknown>:0
  at System.ComponentModel.TypeConverter.ConvertFromString (ITypeDescriptorContext context, System.Globalization.CultureInfo culture, System.String text) [0x00000] in <filename unknown>:0
  at System.ComponentModel.TypeConverter.ConvertFromInvariantString (ITypeDescriptorContext context, System.String text) [0x00000] in <filename unknown>:0
  at System.ComponentModel.TypeConverter.ConvertFromInvariantString (System.String text) [0x00000] in <filename unknown>:0
  at Test.Main (System.String[] args) [0x00000] in <filename unknown>:0

test.cs

using System;
using System.ComponentModel;
public class Test
{
public static void Main(string[] args)
{
        var value = args.Length > 0 ? args[0] :  "4abc2";
        var converter = TypeDescriptor.GetConverter(typeof(int));

        Console.WriteLine("Converting {0}", value);
        Console.WriteLine("Converted reported IsValid as {0}", converter.IsValid(value));

        try
        {
                var result = (int)converter.ConvertFromInvariantString(value);
                Console.WriteLine("Conversion successful {0}", result);
        }
        catch (Exception ex)
        {
                Console.WriteLine("Conversion failed {0}", ex);
        }
}
}