get chop_prefix and s3_bucket also from variable like
get chop_prefix and s3_bucket also from variable like

anomalizer/ngx_aws_auth,trunkclub/ngx_aws_auth,irasnyd/ngx_aws_auth,DreamLab/ngx_aws_auth,irasnyd/ngx_aws_auth,anomalizer/ngx_aws_auth,DreamLab/ngx_aws_auth,passion4code/ngx_aws_auth,passion4code/ngx_aws_auth,trunkclub/ngx_aws_auth