Injection of application-provided CDI bean into extension-provided bean fails

When an application provides a CDI bean, injection of this bean into another bean provided by a portable extension (which is attached to this application) fails.

The specific use case is the PE for Hibernate Validator which contains a class ValidationInterceptor with an injection point of type j.v.Validator. If the application happens to provide a producer for that type, deployment of the application fails with the following error message:

WELD-001408: Unsatisfied dependencies for type Validator with qualifiers @Default
at injection point [UnbackedAnnotatedField] @Inject private org.hibernate.validator.internal.cdi.interceptor.ValidationInterceptor.validator

A test case can be found here. To execute it, pull that branch and run:

mvn clean install -pl integration -Dit.test=InjectionIssueIT

The deployment of that Arquillian test fails with the error above.