ID 241693 - SmartVector error when using file extension .EXR instead of .exr

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Problem summary
When rendering a SmartVector, using the file extension .EXR will not give a warning like other file extensions such as .dpx do, but will give a generic error message on pressing Render. 



The tool tip says to use .exr, but it's not clear .EXR is specifically not allowed.

Customer reported version
Nuke 10.0v4

Customer reported platform
Windows 10

Steps to reproduce

1) Create a Read node and open some footage.

2)  Double-click the SmartVector node to open its properties and enter a file path with file name ending in .EXR, for example C:/temp/SmartVector.###.EXR.

3) Press Render. Rendering the SmartVector will fail and an error message will pop up.

Workaround
Use file extension .exr, not .EXR.

Reproduced by support
Windows 7: 

Nuke 10.0v1 - 4
Mac OSX 10.12 (Sierra): 
Nuke 10.0v1, 10.0v4

Expected behaviour
The SmartVector should be able to write .EXR files just like .exr, because other nodes like the Write node will accept a .EXR file extension. 
A Vector Distort will also accept .EXR files as input, for example if the files written to disk from SmartVector have their extensions changed from .exr to .EXR.

Actual behaviour
Using the file extension .EXR gives an error on trying to render the SmartVector.

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