On selecting a multi-layer image with a combined pass, a "Combined" socket is created and default combined pass socket "Image" is disabled by setting `SOCK_UNAVAIL` flag. When converting into operations, `ImageNode` converts alpha socket on finding any socket with a combined pass without checking the flag. Since commit rB93e2491ee724 an assertion fails when mapping sockets twice because now map `add_new` is used. Reviewed By: jbakker Differential Revision: https://developer.blender.org/D11566