YAHOO.widget.Button
https://github.com/jenkinsci/ec2-plugin/blob/732be1df2be30b256c49db7201685331cb326c5f/src/main/resources/hudson/plugins/ec2/EC2Cloud/computerSet.jelly#L41
jenkinsci/ec2-plugin#997
Fixed in jenkinsci/ec2-plugin#997. Released in 1723.v132eb_a_549b_21.
Fixed in jenkinsci/ec2-plugin#997. Released in 1723.v132eb_a_549b_21.