Dereference ref_dict causes hang

[tbenst]

I've traced a hang when using Pytorch to this line:

bravado-core/bravado_core/spec.py

Line 407 in ac5e46d

if ref_dict is None or not is_ref(ref_dict):

The full trace is here:
https://gist.github.com/tbenst/2b6ef453b37f634f32d856bbdceed71e

Any idea what might be causing this, or how I could troubleshoot?

[macisamuele]

Having more details on how to reproduce the issue could help us more in providing support.
Checking the stacktrace nothing specific rings a bell