Last modified: 2014-01-27 18:16:11 UTC
As described in manual, $wgUpgradeKey should be commented, but LocalSettings.php generated by 1.22.1 installer leaves it uncommented.
Not sure about the behaviour in master and other versions.
As far as I can tell, this was intentionally changed by Tim in 2010. Perhaps the mediawiki.org documentation is simply out of date or misleading?
Thanks for reporting this!
Fixed in <https://www.mediawiki.org/w/index.php?title=Manual:$wgUpgradeKey&diff=892002&oldid=629317>.
As far as I can tell, the setting was not commented out in any released
version of MediaWiki, because of r78437 (95f14f01560d), which merged
r78118 (31eae6a575c1) into REL1_17 prior to the 1.17.0 release.