'I/O operation on closed file' with no associated information

[rod-glover]

Station "HELMUT" in network FLNRO-WMB fails downloads. It does not have any problematic net_var_name associated with it, so this error is not an instance of the one reported in #44 . The error message in the container log is minimal and not very helpful:

Exception ValueError: 'I/O operation on closed file' in <bound method ZipFile.__del__ of <zipfile.ZipFile object at 0x7fe11bc32410>> ignored

It is not preceded or followed (at not least within 10 minutes) by any other error message related to this download. There is no HTTP GET logged for it, nor any stack trace or other diagnostic output. It can be associated with this download only by isolating it in time (on the dev instance, which at present is getting traffic only from me).

Also worth noting: it does not bear the signature of a the standard logging in this app ... so another question is where and how this line gets into the file. Is it a print statement?

[rod-glover]

This message, isolated in time and without context, occurs often with the failing downloads. Originally I thought it was associated with a more informative error message, but that appears to be a separate problem: