ID 444875 - Crash when Pythonically duplicating and flattening channel which contains a custom node

Problem summary
Crash when Pythonically duplicating and flattening channel which contains a custom node

Customer reported version
mari.4.6v3

Customer reported platform
rhel7

Steps to reproduce

1) Open Mari and import attached archive

2) Run the following code, changing the paths for the downloaded ones:

mari.gl_render.registerCustomNodeFromXMLFile(
        'Procedural/Test/HexTile',
        '/path/to/HexTile.xml')
mari.gl_render.registerCustomHeaderFile(
        'MATH_GLSLH',
        /path/to/math.glslh')
mari.gl_render.registerCustomCodeFile(
        'MATH_GLSLC',
        '/path/to/math.glslc')

3) Open the archive

4) Run the following Python code in the Python Console, Mari will crash:

cg = mari.geo.current()
cc = cg.currentChannel()
bc = cg.createDuplicateChannel(cc, 'baked')
print 'Flatten'
bc.flatten()
print 'Flatten done'

Expected behaviour
For Mari to duplicate and flatten the channel

Actual behaviour
Mari crashed

Reproduced by support

This bug has been reproduced in:

Mari 4.6v4 - CentOS 7.6 - Windows 10

Mari 4.6v3 - CentOS 7.6

Unable to reproduce bug in:
Mari 4.6v3 - Windows 10

*This was also verified by development team

Earliest version tested
Mari 4.6v3 - Development team verified the bug