Fix possible nil dereference panics in cache_impl_test
Fix possible nil dereference panics in cache_impl_test

shilpamayanna/heapster,shilpamayanna/heapster,mwringe/heapster,afein/heapster,liubog2008/heapster,mwringe/heapster,apeeyush/heapster,luxas/heapster,Huawei-PaaS/heapster,afein/heapster,luxas/heapster,vishh/heapster-1,skytap/heapster,bruceauyeung/heapster,jackzampolin/heapster,vishh/heapster-1,huangyuqi/heapster,a-robinson/heapster,digideskio/heapster,titilambert/heapster,liuhewei/heapster,vicki-c/heapster,skytap/heapster,mwielgus/heapster,bruceauyeung/heapster,whuwxl/heapster,jackzampolin/heapster,piosz/heapster,burmanm/heapster,whuwxl/heapster,andyxning/heapster,taimir/heapster,liubog2008/heapster,naxhh/heapster,adfin/statster,mdshuai/heapster,aegixx/heapster,mdshuai/heapster,adfin/statster,AlmogBaku/heapster,johanneswuerbach/heapster,wulonghui/heapster,Stackdriver/heapster,piosz/heapster,ravihansa3000/heapster,huangyuqi/heapster,johanneswuerbach/heapster,vicki-c/heapster,aegixx/heapster,bluebreezecf/heapster,saiwl/heapster,bluebreezecf/heapster,andyxning/heapster,apeeyush/heapster,mwielgus/heapster,AlmogBaku/heapster,saiwl/heapster,krzyzacy/heapster,burmanm/heapster,titilambert/heapster,krzyzacy/heapster,ravihansa3000/heapster,wulonghui/heapster,liuhewei/heapster,taimir/heapster,thucatebay/heapster,Huawei-PaaS/heapster,naxhh/heapster,a-robinson/heapster,Stackdriver/heapster,digideskio/heapster,thucatebay/heapster