Last modified: 2009-07-15 19:30:48 UTC
1. Go to Special:Preferences, Rendering, Advanced 2. Select a stub threshold from the menu 3. Save preferences Result: the option is back to "0 B"
According to http://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Stub_link_formatting_threshold_is_not_saved_in_preferences it is actually saved, it just doesn't reflect the correct value in the preferences. So likely an easy fix.
Fixed in r53316.