Load a gamma encoded 2.2 image into node editor. Open scopes panel in UV/Image Editor. Render, (needs camera for compositor, argh!!) :-)

With CM off histogram and Line Tool scopes for render result shows 2.2 gamma output.

With CM on histogram and Line Tool scopes for render result shows what appears to be linearised output.

Render output is still gamma 2.2 as it should be. Scopes incorrect.

Line tool doesn't update with render result change, histogram does.

Luma scope in VSE exhibits same problem when activating 'Convert Float'.