ID 379140 - Certain custom OCIO configs cause black values on 8 bit paint nodes to clamp.

Problem summary
Certain custom OCIO configs cause black values on 8 bit paint nodes to clamp. 

Using the paint tool with 0,0,0 black value returns intensity of 0.004 in all 8 bit, 16 bit and 32 bit nodes  

Customer reported version

4.2v2

Customer reported platform
centos7

Steps to reproduce

1) Open Mari and an example project

2) Create a 8bit Paint node in the Nodegraph with black 0,0,0 values

3) Sample the black with the color picker from the tools palette

result: the color picker returns intensity value of 0.0038604736 

Workaround
The issue is not occurring when using Color nodes 

Reproduced by support

This bug has been reproduced in:

Mari 4.2v2 - Windows 10 - CentOS 7 

Mari 4.2v1 - Windows 10 

Mari 3.4v1 - Windows 10 - OSX 10.13.6 - regression

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Unable to reproduce bug in:
Mari 3.3v1 - Windows 10 - CentOS 7 - OSX 10.13.6

Earliest version tested
Mari 3.3v1 - This issue no longer appears in this version and has regressed

Expected behaviour
The color picker should return 0.000 intensity regardless of bit depth

Actual behaviour
The color picker returns 0.0038604736 intensity in 8bit paint nodes and 0.000 value on 16bit and 32bit