S3 never lists an empty result for another region: a valid region
other than the endpoint's own gets 400 InvalidArgument, "Requests with
bucket-region specified must be made to the corresponding regional
endpoint", with no ArgumentValue. The gateway is a single regional
endpoint, so it now does the same instead of clearing the listing.
Match the region case-insensitively like S3, and check an empty
bucket-region= too by looking for the query argument itself, since an
empty value is not a valid AWS region either.
DualFroz
ee46df2153