Few settings in mozilla.cfg are not taking effect for firefox web browser.

Issue

• Function getenv() is not working in mozilla.cfg

# cat /usr/lib64/firefox/defaults/preferences/autoconfig.js 
pref("general.config.filename", "mozilla.cfg");
pref("general.config.obscure_value", 0);

# cat /usr/lib64/firefox/mozilla.cfg
lockPref("autoadmin.global_config_url","http://mctl-mozilla.ms.com/fcgi-bin/mcontrol.pl/uid=" + getenv("USER") );
lockPref("autoadmin.append_emailaddr",false);