files/ecj-3.3 and files/ecj-3.4 use ls -1r /etc/env.d/gcc/*4.{3,4}* which fails with ls: cannot access /etc/env.d/gcc/*4.{3,4}*: No such file or directory when using dash as /bin/sh. Suggested fix: ls -1r /etc/env.d/gcc/*4.[34]*
There are no eclipse-ecj in java-overlay anymore and the ones in tree use regular Gentoo Java Launchers. Closing as obsolete, thanks for the report though.