System Information
Operating system: Linux-4.15.0-50-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 760/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116

Blender Version
Broken: version: 2.80 (sub 74), branch: blender2.7, commit date: 2019-06-01 22:51, hash: rB079c7f918c81
Worked: (optional)

Short description of error
Change of parameter "Color space" of image texture node, caused change of parameter "Color space" of all image texture nodes based on same image.

Exact steps for others to reproduce the error

1. Go to the Shading workspace
2. Add Image texture node based on external image or make new one
3. Set Color space to sRGB (or any other)
4. Add another Image texture node based on same Image or just make copy of existing one
5. Change Color space to Non color (or any other)

Result:
Color space node parameter will be changed on ALL nodes based on same image. Change affect another materials based on same texture too.

Note: Similar unexpected dependency is for parameter "Single image/Image sequence..."

Bug (Color space) is not relevant for v2.79
but "Single image/Image sequence..." has unexpected dependency in v2.79 too.