S3 silently fails when attempting to create a zero-byte object

[brianaydemir]

This issue comes by way of PelicanPlatform/pelican#2294:

From the viewpoint of the Pelican client, attempting to put a zero-byte object into an S3 origin silently fails. XRootD reports success…

DEBUG[2025-05-05T13:55:47-05:00] Dumping response: HTTP/1.1 200 OK
Content-Length: 3
Connection: Keep-Alive
Server: XrootD/v5.8.1

:-) 
DEBUG[2025-05-05T13:55:47-05:00] Successful upload of 0 bytes

…but a direct examination of the S3 object store indicates that the object was not actually created.