OPTIONAL BACKEND DEPENDENCIES libpng: 1.2.38 X11 connection rejected because of wrong authentication. X connection to localhost:14.0 broken (explicit kill or server shutdown). This happend under some specific circumstances. Build from remote console over 'ssh -Y user@machine su' (remote login as ordinaty user and then changed to root trougth su) where DISPLAY is set properly by ssh. Probably user portage ( emerge/ebuild change user to portage for building process) relly can not authenticate to X. This id wery similar to bug #257634 Reproducible: Always Solution is unset DISPLAY or change it to garabage.
Created attachment 198651 [details] ebuild with unset DISPLAY for build process
Created attachment 198653 [details, diff] patch for ebuild, unset Display Patch version for ebuild. Does the same as previous ebuild.
Fixed in cvs. Thanks!