safe_scan now determines appropriate block sizes for all three passes fixes failure with TestPairScan
safe_scan now determines appropriate block sizes for all three passes
fixes failure with TestPairScan

mohamed-ali/thrust,thrust/thrust,jaredhoberock/thrust,raygit/thrust,zhenglaizhang/thrust,egaburov/thrust,andrewcorrigan/thrust-multi-permutation-iterator,mohamed-ali/thrust,zhenglaizhang/thrust,jaredhoberock/thrust,arnabgho/thrust,xiongzhanblake/thrust_src,sdalton1/thrust,andrewcorrigan/thrust-multi-permutation-iterator,thvasilo/thrust,xiongzhanblake/thrust,jaredhoberock/thrust,thrust/thrust,mohamed-ali/thrust,dachziegel/thrust,zeryx/thrust,sdalton1/thrust,xiongzhanblake/thrust,arnabgho/thrust,sdalton1/thrust,xiongzhanblake/thrust_src,thrust/thrust,thrust/thrust,sarvex/thrust,egaburov/thrust,jaredhoberock/thrust,sarvex/thrust,Ricardo666666/thrust,marksantos/thrust,thvasilo/thrust,xiongzhanblake/thrust,zhenglaizhang/thrust,andrewcorrigan/thrust-multi-permutation-iterator,jaredhoberock/thrust,dachziegel/thrust,zeryx/thrust,zeryx/thrust,marksantos/thrust,egaburov/thrust,dachziegel/thrust,thvasilo/thrust,Ricardo666666/thrust,GrimDerp/thrust,thrust/thrust,xiongzhanblake/thrust_src,sarvex/thrust,GrimDerp/thrust,arnabgho/thrust,GrimDerp/thrust,Ricardo666666/thrust,marksantos/thrust,raygit/thrust,raygit/thrust