ID 414870 - Incorrect blending when using the paint brush and a custom OCIO

Problem summary

Incorrect blending when using the paint brush and a custom OCIO 

This also affects the colours displayed in the viewport which are different that in 4.5v2

Customer reported version
mari.4.6v1

Customer reported platform
centos7

Steps to reproduce

1. Create a project with the attached OCIO profile 

2. Create new layer and paint with blue (0,0,1)

result: Purple fringing on the blending edge 

1. Create a project with the attached OCIO profile

2. Project the attached the macbeth colour chart and compare the colours in the viewport with 4.5v2

result: Difference in the colours 

Expected behaviour
Should be fading without being purple like in 4.5v2

Actual behaviour
Purple fringing on the blending edge 

Workaround
Exporting the channel is exporting the correct colours

Reproduced by support
This bug has been reproduced in:

4.6v1 - Windows 10 - CentOS7 - regression 

Unable to reproduce bug in:
4.5v2 - Windows 10 - CentOS7

Earliest version tested
4.5v2 - This issue doesn't appear in this version and has regressed