BZ-1093174: backporting the fix for [DROOLS-71] Prevent NPE when there is a null value in a list used by a from element
(cherry picked from commit 3c66d62270d343a573748d1d5850ca2054e99917)

Conflicts:

	drools-compiler/src/test/java/org/drools/integrationtests/MiscTest2.java