Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement'

Question

Steps which will reproduce the problem

1. Setting allowedOrigins: ["*"] in config.js as per defined in documentation and version history.
2. Add image in editor from any other domain

Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported. (server_opensave line #73)

Problem occurred in Chrome and Firefox, and in both the latest trunk and 2.7.