I use PyCharm for some of my torch development, and it was PyCharm that detected the issue.  The specific line it reports as the type signature is #884 in file __init__.pyi (1.0.1.post2).
When I was developing on torch 1.0.0, PyCharm did not report a type warning when a list was passed to torch.cat.  The warning only started when I upgraded to 1.0.1.post2 (there were other similar issues I could catalog if it is useful).