ID 303968 - Nuke will sometimes render Rotopaint nodes even when they are not attached nor providing any output in the Viewer

Problem summary
Nuke will sometimes render Rotopaint nodes even when it is not required

Customer reported version
nuke.10.0v6

Customer reported platform
centos6

Steps to reproduce

1) Launch Nuke and open the attached script

2) Navigate around the time-line to see if Nuke will read through the script and read one of the unattached roto nodes. (Select random frames on the time-line)

3) Sometimes the issue can be reproduced by clearing the users Cache (Cache tab, Clear all), attaching the BG input of RotoPaint4 to Saturation1, changing the Source parameter of the Strokes in Rotopaint 4 to BG instead of FG then with the rotopaint not being connected to anything else and the viewer still connected to Kronos1. The user might see Rotopaint 4 update despite not being connected to anything. This issue is very difficult to reproduce so it will not always happen.


Workaround
Unknown.

Reproduced by support
Nuke 11.0v1 - CentOS 6.9
Nuke10.0v6 - CentOS 6.9


Unable to reproduce by support

Nuke 11.0v1 - MacOS 10.12 - Windows 10
Nuke 10.5v5 - CentOS 6.9 - MacOS 10.12 - Windows 10
Nuke10.5v1 - CentOS 6.9 - MacOS 10.12 - Windows 10
Nuke10.0v6 - MacOS 10.12 - Windows 10
Nuke10.0v1 - CentOS 6.9 - MacOS 10.12 - Windows 10
Nuke9.0v9 - CentOS 6.9 - MacOS 10.12 - Windows 10
Nuke9.0v1 - CentOS 6.9 - MacOS 10.12 - Windows 10


Earliest version tested
Nuke 9.0v1 - CentOS 6.9 - MacOS 10.12 - Windows 10
Enough features in the example script did not exist prior to 9.0v1 to warrant further testing.


Expected behaviour
Nuke would render without calculating the rotopaint nodes (Rotopaint3 and Rotopaint4) as they are not connected to anything nor outputting to anything.

Actual behaviour
Very rarely Nuke would render one of the Rotopaint nodes (Rotopaint3 and/or Rotopaint4) for a single frame, all attempts at reproduction within the same script and same Nuke version were unsuccessful.