eevee: mix holdout with transparent fails

mixing holdout with transparent in an eevee shader behaves unexpected.

reproduce: holdout and transparent in a mix node.

• it looks like the transparent bsdf is blending into black while bekoming alpha-ed out.
• the material blendmode is "alpha blend". but other material blendmodes dont work aswell.

on 0.5 mixed, the holdout is half there, as expected, but transparent looks like color(0.5,0.5,0.5,0.5)

solution? i assume, its internally blending to color(0,0,0,0) but the transparent needs (1,1,1,n) to stay invisible, and in this case should be at color(1,1,1,0.5) when 0.5 mixed. (since it seems to not use the alpha information internaly and, if my assumption is correct, holdout just is alpha and doesnt need its own color data)

• so for the transition it might work correct if holdout takes rgb from the material to be mixed with.
• or maybe give the holdout node an rgb input for mixing situations.

i posted this as a bug because i think blending transparent into alpha-out should make stuff more alpha and not more alpha and less transparent.

got this answer: "To my knowledge this is working as it is supposed - holdout shader will not "pass" any data through therefore it will be completely black. Unfortunately I am not able to provide "workaround" for this case, but please try asking on forums for help, or propose new features on appropriate portals."

but: in cycles its working like it should and since cycles and eevee should behave more or less the same, i think it actually is a bug.