Misleading error message during S3 upload if overwrite is not enabled

[atschabu]

With overwrite set to the default value of 'false', the error message in S3 Upload task complains about matching md5 check, eventhough the md5 get's never checked. https://github.com/classmethod/gradle-aws-plugin/blob/develop/src/main/java/jp/classmethod/aws/gradle/s3/AmazonS3FileUploadTask.java#L67

Furthermore this check should be part of the 'up-to-date' check, so it is clearly visible that the upload was skipped, not hidden in the logs.

[xelibrion]

+1, just found out it happened to me as well

Moreover, I don't think not overwriting files is a reasonable default setting for a uploading build artifacts.