Running qc0_mclachlan.par from the par directory of a 2016_05 checkout I get:
WARNING level 1 from host 127.0.0.1 process 0 while executing schedule bin CCTK_PARAMCHECK, routine ML_BSSN_Helper::ML_BSSN_ParamCheck in thorn ML_BSSN_Helper, file configs/sim/build/ML_BSSN_Helper/Parameters.c:157: -> Parameter ML_BSSN::my_initial_boundary_condition is outdated; please update the parameter file. Do not use this parameter, and set up initial boundary conditions as usual.
Since qc0_machlan.par is a typical "beginner's file" and our tutorial mentions it, we should update so that it does not produce warnings when run anymore. We should also I believe update the paramwarn message to be more helpful since likely the user did not know what the "usual way to set up initial boundary conditions" is, otherwise they'd have done so :-).
Major as this should be be fixed for the next release.