Fix Maya legacy renderlayer being unable to duplicate (it doesn't show up correctly, but it does create a new renderLayer node visible when Show DAG nodes only is disabled)

maya_renderlayer_fix_unable_to_duplicate.py

# Fix Maya bug where you cannot duplicate a renderlayer correctly bug
# This is with Legacy Renderlayers, not Render Setup.
# Bug has been found in both Maya 2018 + 2019

import maya.cmds as mc

# Recreate all renderlayer overrides (.adjustments)
for layer in mc.ls(type="renderLayer"):

    attr = layer + ".adjustments"
    indices = mc.getAttr(attr, multiIndices=True) or []
    
    connections = []
    for index in indices:
        
        # Collect current connection
        index_attr = "{plug}[{index}]".format(plug=attr, index=index)
        src = cmds.listConnections(index_attr + ".plug", 
                                   source=True, 
                                   plugs=True)[0]
        value = cmds.getAttr(index_attr + ".value")
        connections.append((src, value))

        # Remove the entry and break any connections
        mc.removeMultiInstance(index_attr, b=True)
        
    # Recreate the overrides
    for i, (src, value) in enumerate(connections):
        cmds.connectAttr(src, layer + ".adjustments[{0}].plug".format(i))

It ran this time but sadly no joy. :/

Force renderlayer editor refresh

mel.eval('updateEditorRenderLayer "RenderLayerTab"')
Fixing missing renderLayerId connection for: BTY_ASIA1
prop_bridge:renderLayerManager.renderLayerId[2] -> BTY_ASIA1.identification
Fixing missing connection to defaultRenderingList for: BTY_ASIA1
BTY_ASIA1.message -> defaultRenderingList1.rendering