ID 517655 - Values higher than 2 can appear clamped when displayed through the View Transform in ACES projects

Problem summary
Values higher than 2 can appear clamped when displayed through the View Transform in ACES projects
 
This issue affects both images imported into the Image Manager and Paint nodes.
 
Customer reported version
Mari 4.8
 
Customer reported platform
n/a
 
Steps to reproduce
 
1) Download the attached EXR
 
2) Open an ACES project
 
3) Import the image into the Image Manager. Set the Colorspace as 'ACES - ACEScg'
 
4) View the image, specifically the bright hair areas which contain values above 1
 
Expected behaviour
Values above 1 should be remapped for displaying through the View Transform (screenshots from Mari 4.7v7):
 
KodakMarcie_HighValues_ACEScg_16bit.exr:

 
SmoothRamp_0-10_16bit.exr:

 
Actual behaviour
Values above 2 appear clamped, which is noticeable in the hair in this test image (screenshots from Mari 4.8v4):
 
KodakMarcie_HighValues_ACEScg_16bit.exr:

 
SmoothRamp_0-10_16bit.exr:

 
Workaround
Unknown.
 
Reproduced by support
This bug has been reproduced in:
Mari 5.0v4 - Windows 10 - CentOS 7.9
Mari 4.8v4 - Windows 10
 
NOTE: This bug is also reproducible in the versions listed below, but the clamping appears worse (originally logged under ID 511533):

Mari 5.0v3 - Windows 10 - CentOS 7.9
Mari 4.8v3 - Windows 10
Mari 4.8v1 - Windows 10 - CentOS 7.9 - regression
 
Unable to reproduce bug in:
Mari 4.7v7 - Windows 10 - CentOS 7.9
 
Earliest version tested
Mari 4.7v7 - This issue doesn't appear in this version and has regressed