ID 430259 - The Bilateral node gives the incorrect result when the Guide Channels knob is set to "all"

Problem summary
The Bilateral node gives the incorrect result when the Guide Channels knob is set to "all".

This bug is reproducible with the Bilateral2 node and the C_Bilateral 

Customer reported version
Nuke 12.1v1

Customer reported platform
macOS 10.13

Steps to reproduce

1) Open Nuke.

2) Create a Roto node and create a Bezier shape in the Viewer.

3) Create a Bilateral node and connect it downstream from the Roto node. 

4) Create a CheckerBoard and connect it to the Guide input of the Bilateral node.

5) Apply the following settings to the Bilateral node:

6) Set the Guide Channels knob to "all" and view the alpha channel on the Bilateral node. Compare it to the result of setting the Guide Channels knob to "rgba".

Expected behaviour
In this example, setting the Guide Channels to "rgba" or "all" should give the same result as the CheckerBoard (the Guide input) only has rgba channels.

Actual behaviour
The alpha channel looks soft, much like if a Blur has been applied.

Workaround
Unknown.

Reproduced by support

This bug has been reproduced in:
Nuke 12.1v1 - macOS 10.14 (Mojave) - Windows 10 - Linux CentOS 7

Reproduced in the following versions with the C_Bilateral node:

Nuke 12.0v1 - macOS 10.14 (Mojave) - Windows 10 - Linux CentOS 7

Nuke 11.0v1 - macOS 10.14 (Mojave)

Nuke 10.5v1 - macOS 10.14 (Mojave) - Windows 10 - Linux CentOS 7

Earliest version tested
Nuke 10.5v1

The C_Bilateral node did not exist before this version.

The Bilateral node did not take a Guide input until Nuke 12.1v1