PyMel error when calling .root() on top level transform in Maya 2020

[windxu88]

Run the following script in Maya 2020

import pymel.core as pm
py_node = pm.PyNode("persp")
root_node = py_node.root()
print(root_node)

Result: One error as below is returned:
# Error: MayaNodeError: file /Applications/Autodesk/maya2020/Maya.app/Contents/Frameworks/Python.framework/Versions/Current/lib/python2.7/site-packages/pymel/core/nodetypes.py line 1323: Maya Node does not exist (or is not unique):: u'None' #

In Maya 2019, it returns persp.

[FUJonathan]

I know this is an old issue, but I just ran into it and can confirm that it still happens in Maya 2022.

[FUJonathan]

As a workaround, I'm using this function, which splits the long name of the node by the pipe character and then makes a new PyNode from the first non-empty item in the list. Not sure if it'll work in all situations but it's sufficient for my needs.

import pymel.core as pm

def get_root(node):
    # longName is of the format '|root|parent|child', starting with an initial pipe
    long_name = node.longName()
    parent_names = long_name.split(u'|')
    return (None 
            if len(parent_names) <= 1
            else pm.PyNode(u'|{}'.format(parent_names[1])))