Set LC_CTYPE  in the README for macOS
Without setting the correct LC_CTYPE, demo cluster creation fails on
master branch.
@@ -69,6 +69,7 @@ sudo chown $USER:admin /usr/local/gpdb
cat >> ~/.bashrc << EOF
ulimit -n 65536 65536 # Increases the number of open files
export PGHOST="$(hostname)"
+export LC_CTYPE="en_US.UTF-8"
EOF
cat << EOF
