ID 249973 - EXR Read does not update its colorspace default reliably, when float files default is changed in Project Settings,

Problem summary
REGRESSION 10.0v3
When float files default in Project Settings is changed from linear to sRGB and back to linear,
EXR Read does not update its colorspace back to default linear, unless the script is saved and re-opened.

Customer reported version
nuke.10.0v4

Customer reported platform
centos6

Steps to reproduce

-Read in an exr file.
-Duplicate the Read node twice.
-Leave the colorspace of Read1 node on 'default (linear)'
-Set the colorspace of Read2 node to 'linear'
-Set the colorspace of Read3 node to 'sRGB'
-In the viewer, 1 & 2 will match, 3 will differ

-Open project settings and change default LUT 'float files' from linear to 'sRGB'
RESULT:
-colorspace of Read1 node changes to 'default (sRGB)'
-colorspace of Read2 node remains set to 'linear'
-colorspace of Read3 node remains set to 'sRGB'
-In the viewer, 1 & 3 will match, 2 will differ
AOK, Read1 has updated to the new default setting

-Open project settings again and change default LUT 'float files'  back to linear
INCORRECT RESULT:
-colorspace of Read1 node REMAINS 'default (sRGB)'
-colorspace of Read2 node changes to 'linear'
-colorspace of Read3 node remains set to 'sRGB'
-In the viewer, 1 & 3 will match, 2 will differ
Read1 has not updated back to 'default (linear)' as expected
-Save script and Re-open
-Now Read1 has updated to the correct colorspace 'default (linear)'

Workaround
Unknown

Reproduced by support
10.0v3-10.0v5 and 10.5v1.  This is a regression, it works correctly in 10.0v2 and before
MaxOS 10.11.5 and 10.10.5

Expected behaviour
When Project Settings floatLut knob is changed from linear to sRGB and then back to linear,
default EXR Read should update its colorspace back to default (linear) automatically

Actual behaviour
When Project Settings floatLut knob is changed from the linear to sRGB and then back to linear,
default EXR Read does not update its colorspace back to default (linear), unless the script is saved and re-opened.