Description of problem:
When using multiple constraints connected with logical or, the rules can't be compiled. The compiler complains that DefaultFactHandle  can't be cast to String.

Version-Release number of selected component (if applicable):
Drools 6.0.0.Beta3, Drools master (2013-06-06)

How reproducible:
Pull request with the test submitted on Github

Steps to Reproduce:
1. run testStrWithLogicalOr JUnit test

Actual results:
Rules don't compile

Expected results:
Rules compile and correct number of rules are fired

Additional info:
It does not matter whether constraint with str evaluator is first or second.