I have embedded an image as a Base64 data URI in a background css:

background: url("data:image/png;base64,iVBORw0KGgoAAAANSUh...") no-repeat 0 bottom;

It works fine until I minify the CSS. Then the code for the data: protocol gets stripped out.

background: url("image/png;base64,iVBORw0KGgoAAAANSUh...") no-repeat 0 bottom;

Turn off minify CSS and all is fine again. How should I best report this bug? Have searched but not found it mentioned.