Allow abc as USER_NAME

Author: thespad

root/etc/s6-overlay/s6-rc.d/init-adduser/run

@@ -1,7 +1,7 @@
 #!/usr/bin/with-contenv bash
 # shellcheck shell=bash
 
-if [[ -n "$USER_NAME" ]] && grep -q "^${USER_NAME}" /etc/passwd; then
+if [[ -n "$USER_NAME" ]] && [[ "$USER_NAME" != "abc" ]] && grep -q "^${USER_NAME}" /etc/passwd; then
     echo "*** USER_NAME cannot be set to an user that already exists in /etc/passwd. Halting init. ***"
     sleep infinity
 else