Validating rules that extend others is broken

Description of problem:

If you create a rule that extends another and "validate" the rule; you receive an error "Unable to resolve parent rule, please check that both rules are in the
same package". Saving the rule works OK and no error messages are given.

This is caused by the validation service only loading the single rule and not the rule it extends too. Rule validation should load all rules (ideally if a rule extends another, otherwise only the single rule is OK).

Version-Release number of selected component (if applicable):

6.0.0.GA

How reproducible:

Always

Steps to Reproduce:
1. Create "rule 1"
2. Create "rule 2" that extends "rule 1"
3. Click validate on "rule 2"

Actual results:

Validation error message is shown.

Expected results:

No validation error message is shown.