I am trying for enforce some configuration details with Firefox 31
(SLED11 SP3) and 38 (SLED11 SP4). More specifically I want to limit the
browser cache size and set a default value for the home page.

Following http://kb.mozillazine.org/Locking_preferences I created two
files within /usr/lib64/firefox/browser/defaults/preferences:

# cat local-settings.js
pref("general.config.obscure_value", 0); // only needed if you do not
want to obscure the content with ROT-13
pref("general.config.filename", "mozilla.cfg");

# cat mozilla.cfg
lockPref("browser.cache.disk.capacity", 102400);
defaultPref("browser.startup.homepage", "http://www.example.com/");

Both files share the 0.0 644 rights with the configuration files from
the SLED packages MozillaFirefox and MozillaFirefox-branding-SLED.

As a first result the browser will not start anymore:
Error message: "Failed to read the configuration file. Please contact
your system administrator." That is me... :-)

Any ideas on how to make this work? Do I really have to rot-13 the files
as suggested by the old Wiki article from mozillazine.org?