When plugin startup experiences panic, plugin writes known string to stdout so plugin manager can intercept the "Unrecognized remote plugin message" and instead return the panic message. DO not retry plugin startup if initialisation fails. #3732.

When plugin startup experiences panic, plugin writes known string to stdout so plugin manager can intercept the "Unrecognized remote plugin message" and instead return the panic message. DO not retry plugin startup if initialisation fails. #3732. #7229