revised tests for left_shift and right_shift ufuncs.
revised tests for left_shift and right_shift ufuncs.

The tests were fragile when taking into account “undefined behavior”.
False failures could happen because numba happened to give a different
result on undefined behavior.
sklam/numba,seibert/numba,ssarangi/numba,pitrou/numba,ssarangi/numba,stefanseefeld/numba,jriehl/numba,GaZ3ll3/numba,pombredanne/numba,seibert/numba,IntelLabs/numba,IntelLabs/numba,sklam/numba,gdementen/numba,numba/numba,seibert/numba,pombredanne/numba,stonebig/numba,cpcloud/numba,stuartarchibald/numba,ssarangi/numba,numba/numba,GaZ3ll3/numba,gdementen/numba,seibert/numba,stuartarchibald/numba,seibert/numba,gmarkall/numba,GaZ3ll3/numba,sklam/numba,stuartarchibald/numba,ssarangi/numba,pombredanne/numba,numba/numba,pombredanne/numba,gmarkall/numba,sklam/numba,stefanseefeld/numba,jriehl/numba,cpcloud/numba,gmarkall/numba,stefanseefeld/numba,cpcloud/numba,IntelLabs/numba,pitrou/numba,ssarangi/numba,stuartarchibald/numba,jriehl/numba,GaZ3ll3/numba,numba/numba,pitrou/numba,pombredanne/numba,IntelLabs/numba,cpcloud/numba,jriehl/numba,stonebig/numba,cpcloud/numba,stefanseefeld/numba,stonebig/numba,sklam/numba,pitrou/numba,IntelLabs/numba,stonebig/numba,gmarkall/numba,stefanseefeld/numba,gdementen/numba,stuartarchibald/numba,numba/numba,gmarkall/numba,pitrou/numba,gdementen/numba,GaZ3ll3/numba,jriehl/numba,gdementen/numba,stonebig/numba