MPI number of cores problem for Analysis macro

[shruthivis]

If I have run Replica Exchange sampling with say 4 cores (so that I have 4 stat files and so on in the output) and try to run the analysis with more than 4 cores PMI complains with an unhelpful error and the job is hung.
Error:
IndexError: list index out of range
skip_clustering=True
File "/pico1/home/shruthi/imp-clean/build/lib/IMP/pmi/macros.py", line 1238, in clustering
po = IMP.pmi.output.ProcessOutput(my_stat_files[0])

Example
data directory: park1/shruthi/sampcon/pmibugs/1AVX/1AVX_4.1
Running this command which uses the Analysis macro
mpirun -np 8 /bass1/home/shruthi/imp-clean/build/setup_environment.sh python /salilab/park1/shruthi/data/sampcon/scripts/cluster/get_top_models_each_run.py 10