PIG-4930: Skewed Join Breaks On Empty Sampled Input When Key is From Map (nkollar via rohini) . Original patch ommitted as part of previous checkin of PIG-4923
PIG-4930: Skewed Join Breaks On Empty Sampled Input When Key is From Map (nkollar via rohini) . Original patch ommitted as part of previous checkin of PIG-4923

git-svn-id: c4d08399a8c07badad33cbf13a0909bacb78f41f@1777851 13f79535-47bb-0310-9956-ffa450edef68

kexianda/pig,kexianda/pig,kexianda/pig,kexianda/pig,kexianda/pig,kexianda/pig,kexianda/pig