ID 408969 - Arnold Standard Surface shader's opacity map with 0.00 intensity displays black

Problem summary
Arnold Standard Surface shader's opacity map with 0.00 intensity displays black instead of transparent

Customer reported version
4.5v2

Customer reported platform
windows10

Steps to reproduce

1) Open Mari and create a new project using the Arnold Standard Surface shader with opacity channel 

2) Add an environment light from the Lights palette 

3) Add a procedural color layer to the Opacity channel with 0.00 intensity 

result: The object is displayed as full black

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Expected behaviour
Should be all transparent

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Actual behaviour

The object displays pure black  

Workaround
Using 0.001 fixes the issue

Reproduced by support
This bug has been reproduced in:

4.5v2 - Windows 10 - CentOS 7 

4.5v1 - Windows 10 - CentOS 7

Earliest version tested
4.5v1 - This feature did not exist before this version