Dynamic validation rules fail when using both regex and required true

[sembogaarts]

Versions:

• VueJs: 2.3.3
• Vee-Validate: 2.0.0-rc.8

Description:

When switching between dynamic (computed) validation rules, containing a regex and required true:

{
    rules: {
        required: true, 
        regex: /^([0-9]{4})$/
    }
}

switching to:

{
    rules: {
        required: true, 
        regex: /^([a-z]{5})$/
    }
}

The validator does not update the regex validation. After some testing it appears that when both validation rules contain "required: true", the regex will not update when the rule is changed.

Steps To Reproduce:

Working situation (If one rule is not required):
https://jsfiddle.net/gcnf5ucn/12/

NOT working situation (both rules required):
https://jsfiddle.net/gcnf5ucn/11/

Workaround:

When you change the order of the rules object, it seems to work.
Working demo: https://jsfiddle.net/gcnf5ucn/13/