Note the contents of build/target/wildfly-core-2.0.0.CR4-SNAPSHOT/standalone/configuration/logging.properties

$ ./build/target/wildfly-core-2.0.0.CR4-SNAPSHOT/bin/jboss-cli.sh
You are disconnected at the moment. Type 'connect' to connect to the server or 'help' for the list of supported commands.
[disconnected /] embed-server --std-out=echo

Check the contents of build/target/wildfly-core-2.0.0.CR4-SNAPSHOT/standalone/configuration/logging.properties, the file is empty.

Starting standalone will restore the default contents.