stan-dev/rstan — pull request #85 by bgoodri (2014-07-11 15:43:13+00:00)
Title: force rho_hat to be 0 if it is NaN due to the variable being constant

Fix problem with monitor() on a constant variable that Sebastian encountered here:
https://groups.google.com/d/msg/stan-users/HBewhdW1u88/tAcAIkiFdV4J