Fix infinite loop in sparselu (grafted from 2d2c9e966f5ee619a414defa506e9e194a6572f0)
Fix infinite loop in sparselu
(grafted from 2d2c9e966f5ee619a414defa506e9e194a6572f0)

--HG--
branch : 3.2

robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen