ID 381818 - Switching the scalar/color toggle in a procedural color node results in a difference in the color values

Problem summary
Switching the scalar/color toggle in a procedural node results in difference in color values when using a custom OCIO config on OSX and a scalar channel

Customer reported version

Customer reported platform
10.13

Steps to reproduce

1) Open Mari and create an example project with the attached colorspace 

2) Create a Scalar channel in the Node Graph

3) Create a Color node with intensity of 0.5

4) Open the Node Properties for the Color node and switch the toggle from Scalar to Color

Result: there is a difference in the color value when the Color procedural node is set to Scalar or to Color. This extends to all procedural nodes in a scalar channels

Workaround
Unknown.

Reproduced by support

This bug has been reproduced in:
Mari 3.4v4 - OSX 10.12.6 - regression

Unable to reproduce bug in:

Mari 3.4v4 - Windows 10 - CentOS 6.9
Mari 3.4v3 - OSX 10.12.6

Mari 3.4v2 - OSX 10.12.6

Earliest version tested
3.4v3 - This issue no longer appears in this version and has regressed

Expected behaviour
The color should not be affected by the Color/Scalar toggle 

Actual behaviour
The color is affected by the Color/Scalar toggle