No additional information provided when a "response payload not completed" error is raised

Version
3.18.6

Describe the bug

Pulp download of package fails silently if a proxy uses "data trickling" and later fails

To Reproduce

• A web proxy (example: McAfee Web Gateway) uses "data trickling" to keep a session open for Pulp
  and downloads the package to scan it for viruses.
• If everything is ok, the proxy then lets the whole file through.
• If the package is however blocked on the web proxy the proxy prints an error messages to the end
  of the file and then closes the connection
• If that happens pulp only reports the error message "Response payload is not completed" without
  showing exactly which package failed to download

Actual results:

• Error message "Response payload is not completed" without further information which package failed to download

Expected results:

• Pulp should show the full URL of the failed package and the complete error message provided by the upstream proxy

Additional context
https://bugzilla.redhat.com/show_bug.cgi?id=2187295

No files or tests are named; start by reproducing the Pulp download through a proxy that trickles data and then blocks the package, focusing on the handling of the “Response payload is not completed” error. Done means the failure identifies the full package URL and preserves the complete upstream proxy message.