Number Field Accept Alphanumeric Value

Steps to replicate:

1. create a new Number Field type custom field
2. create an issue an enter "3g"
3. JIRA does not warn users but accept the value "3" as the Number Field value

This is reproducible in JIRA 4.0 andad 4.0.2. However, this is not reproducible in JIRA 4.1 and above. For JIRA 4.1, JIRA will throw '3g' is an invalid number.