"Save as New Version" tool in Houdini right-click menu on nodes, for https://jurajtomori.wordpress.com/2018/12/22/houdini-tip-save-modified-asset-as-new-version/

OPmenu.xml

<?xml version="1.0" encoding="UTF-8"?>

<menuDocument>
    <menu>
        <scriptItem id="opmenu.save_as_new_version">
            <insertAfter>opmenu.saveoptype</insertAfter>
            <label>Save as New Version</label>
            <context>
            <expression>
<![CDATA[
node = kwargs["node"]

if node.matchesCurrentDefinition():
    return False

if not node.isNetwork():
    return False

hda_def = node.type().definition()

if not hda_def:
    return False
    
options = hda_def.options()

if not options.lockContents():
    return False

if node.isInsideLockedHDA() and not node.isEditableInsideLockedHDA():
    return False

if hou.hda.safeguardHDAs():
    return False

if not node.type().isWritable():
    return False

if not node.type().areContentsViewable():
    return False

return True
]]>
            </expression>
	    </context>
            <scriptCode>
<![CDATA[
# unlocked node
unlocked_node = kwargs["node"]
unlocked_def = unlocked_node.type().definition()
current_name = unlocked_node.type().name()

# disk path of asset
asset_path = unlocked_def.libraryFilePath()

# get new name and save a new version
choice, new_name = hou.ui.readInput(message="Please enter new node name", title="New name", buttons=("OK", "Cancel"), close_choice=1, initial_contents=current_name)
if choice == 0:
    node_type_category = unlocked_node.type().category()
    unlocked_def.copyToHDAFile(asset_path, new_name=new_name)

    # get definition of new version and update from unlocked node
    new_type = hou.nodeType(node_type_category, new_name)
    new_def = new_type.definition()
    new_def.updateFromNode(unlocked_node)

    # change unlocked node to the new definition and match current definition
    unlocked_node = unlocked_node.changeNodeType(new_name)
    unlocked_node.matchCurrentDefinition()
]]>
            </scriptCode>
        </scriptItem>
    </menu>
</menuDocument>