Some OpenStack environments may have Swift speaking HTTP2, possibly when behind a reverse proxy. It would fail with:

Cannot extract names from response with content-type: []

This error affected gophercloud v0.17.0 and below for listing containers, and was fixed in a seemingly unrelated patch via b7d5b2c#diff-775ab0e4f42bef31b7fc4b024f3be57b813ff2756645efab1869777bf589eefbR75

The error still affects listing objects. We may want to also treat an empty content type as text/plain there.