ID 556045 - Nuke renders can be cancelled by a get(channels=0xf) Warning under certain circumstances

Problem summary:
Nuke renders can be cancelled by a get(channels=0xf) Warning under certain circumstances

Customer reported version:
Nuke 14.0v5

Customer reported platform:
Windows 10

Steps to reproduce:
1) Download the attached render_test.nk script.

2) Render the file from the Command Line, with this command or similar:

"C:\Program Files\Nuke14.0v6\Nuke14.0.exe" -x C:\path\to\the\render_test.nk

3) Observe the Warnings printed to the Terminal:

Warning: RotoPaint1: get(channels=0xf), but request(channels=0x7)Warning: RotoPaint1: get(channels=0x8), but request(channels=0x7)

 

 
Expected behavior:
When rendering, frames should complete or error without cancelling subsequent frames.
 
Actual behavior:
Rendering the render_test.nk script can cancel itself on an arbitrary frame, and no remaining frames are rendered.
This issue is not entirely consistent, but in most instances a number of frames will complete before the render is cancelled. 
 
Additionally, on occasion only the first Warning appears, but the render is still cancelled:

 
When rendering with the Frame Server, this is problem is observable as a Render error: Cancelled error message:

 
Workaround:
This problem may be prevented by adding a Remove node set to keep RGB only, or changing the Write node's channels from all to RGB.
 
Reproduced by Support in:
Nuke 16.0v1 - Windows 10
Nuke 14.0v6 - Windows 10, CentOS 7
Nuke 14.0v1 - Windows 10, CentOS 7
Nuke 13.2v1 - Windows 10 
Nuke 13.1v5 - Windows 10 
Nuke 13.1v4 - Windows 10 
Nuke 13.1v3 - Windows 10 - Regression?
 
Unable to reproduce bug in:
Nuke 13.1v2 - Windows 10, CentOS 7
Nuke 13.1v1 - Windows 10, CentOS 7
Nuke 13.0v1 - Windows 10, CentOS 7
 
The exact regression is unknown, due to the issue's inconsistency.
 
Earliest version tested:
Nuke 13.0v1 - This issue doesn't appear in this version and has regressed