#183 s3cmd falls back to sigv2 when underscore is in bucket name

[L J]

When using s3cmd to upload to a bucket where the name has an underscore in it, it falls back to signature_v2, and when the bucket has no underscore it uses signature_v4. I dont think buckets with underscores and capitals need to be changed or not used, its just that new buckets can not be created with those in the names.

I have tested this on the latest version (2.0.2).

[Florent Viard]

Issue solved in release 2.1.0.