Applied fix from trunk for revision: 1609406 
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Fixed bug reported by Christian Carlow in OFBIZ-5599: Facility Pick Stock Moves "Cannot compare: r-value is null" error when ProductFacilityLocation.minimumStock is not set.



git-svn-id: https://svn.apache.org/repos/asf/ofbiz/branches/release12.04@1609408 13f79535-47bb-0310-9956-ffa450edef68