Exporting RGBA preview image clips color components

[u3shit]

Material Maker version: 1.3

OS/device including version: Linux amd64, amdgpu and intel

Issue description:
Exporting a preview from a color (RGB) output to an EXR file correctly preserves values outside 0..1. Doing the same with an RGBA output clamps values to 0..1, even if I export to EXR, which is really annoying.

Steps to reproduce:
bug.json
Rename it to .ptex and open it. The custom nodes produce the same output, but the upper one uses Color and the lower one uses RGBA output (a=1). Right-click in Preview 2D and export the image to EXR. Open the EXR file with something that supports HDR images properly and check the values (I use gimp and it's color picker tool with info window). Only the image exported from the Color node will have negative values or values > 1.