ID 369350 - Enabling Colorspace in a Merge node changes the colour values picked by the Color Picker when using certain OCIO Configurations

Problem summary

Enabling Colorspace in a Merge node changes the colour values picked by the Color Picker when using certain OCIO Configurations

Customer reported version

Mari 4.1v2

Customer reported platform
windows7

Steps to reproduce

1) Open the attached Archive and download and exact the attached OCIO Config

2) Open File>Settings, and set the OCIO COnfig to Custom and set the Custom OCIO Config to the extracted ocio.config file

3) Open the Color Picker, and sample the darker grey, it will return sRGB values of 74 and linear values of 51

4) Open the Node graph

5) Open the node properties for the Merge node

6) Disable Colorspace Enabled

7) Sample the darker grey again, it will now return sRGB values of 74 and linear values of 50

This does not appear to happen for nuke-default and aces OCIO Configs

Workaround
Use a different OCIO Config, such as nuke-default or aces

Reproduced by support

This bug has been reproduced in:

Mari 4.2v1 - Windows 10, CentOS 6.9

Mari 4.1v2 - Windows 10, CentOS 6.9

Mari 4.1v1 - Windows 10, CentOS 6.9 - regression

Unable to reproduce bug in:

Mari 4.0v4 - Windows 10, CentOS 6.9

Earliest version tested
Mari 4.0v4 - This issue no longer appears in this version and has regressed
 

Expected behaviour
For the color picker values to be consistent when then Merge node's colourspace is enabled or disabled

Actual behaviour
For some OCIO Configs, the values change