Comparison between int and None fails under python3 when resuming MCMC

[joezuntz]

When setting resume=True and calling via the API there is a crash, which I think comes from a change between python 2 and python 3. In py2 you can do, e.g. 1>None and it will just return False, but in py3 it raises an error. I think that's what's happening in the traceback below.

[SNIP some external bits]
    self.cobaya_run(info)
  File "/usr/local/lib/python3.6/dist-packages/cobaya/run.py", line 64, in run
    modules=info.get(_path_install)) as sampler:
  File "/usr/local/lib/python3.6/dist-packages/cobaya/sampler.py", line 188, in get_sampler
    info_sampler[name], posterior, output_file, resume=resume, modules=modules)
  File "/usr/local/lib/python3.6/dist-packages/cobaya/sampler.py", line 150, in __init__
    self.initialize()
  File "/usr/local/lib/python3.6/dist-packages/cobaya/samplers/mcmc/mcmc.py", line 59, in initialize
    if self.resuming and (max(self.mpi_size, 1) != max(get_mpi_size(), 1)):
TypeError: '>' not supported between instances of 'int' and 'NoneType'

[JesusTorrado]

Hi Joe,

Thanks for the issue! Would you mind checking if the last commit fixes it?

Cheers
Jesús

[joezuntz]

Hi Jesus,

That does seem to fix it - thanks! I've hit another issue which I'll open separately.

Cheers,
Joe