Negative range HTTP requests returning 501

[domdfcoding]

Describe the bug
Until recently (certainly at least September 2022) it was possible to make HTTP requests to files.pythonhosted.org with the Range header set to e.g. bytes=-100 to get the last 100 bytes of the file. As of March 2023 an error 501 is returned with the message "Unsupported client range".

Expected behavior
The last 100 etc. bytes of the file are returned.

To Reproduce

• Failing example (last 100 bytes): curl -v -H Range:bytes=-100 https://files.pythonhosted.org/packages/94/e2/0a5630e43ca0b21ca891ec3a697bdb98a25663e27ebd1079ab55e8c68e72/domdf_python_tools-2.9.1-py3-none-any.whl
• Working example (first 100 bytes): curl -v -H Range:bytes=0-100 https://files.pythonhosted.org/packages/94/e2/0a5630e43ca0b21ca891ec3a697bdb98a25663e27ebd1079ab55e8c68e72/domdf_python_tools-2.9.1-py3-none-any.whl

My Platform
Can reproduce on multiple computers and ISPs in the north and south of England. The connections are to both Fastly's LON and LCY data centres.

Additional context

Requests with a start and end byte (e.g. bytes=100-200) work fine.

[miketheman]

Duplicate of #12823