After upgrading to SVN 1.16 trunk rev. 66620, MediaFunctions fails with error message:

'Detected bug in an extension! Hook efMediaFunctionsSetup failed to return a value; should return true to continue hook processing or false to abort.' in includes/Hooks.php:155

Stack trace:
#0 /usr/share/mediawikistaging/phase3/includes/parser/Parser.php(176): wfRunHooks('ParserFirstCall...', Array)
#1 /usr/share/mediawikistaging/phase3/includes/MessageCache.php(659): Parser->firstCallInit()
#2 /usr/share/mediawikistaging/phase3/includes/GlobalFunctions.php(708): MessageCache->transform('$1 - {{SITENAME...')
#3 /usr/share/mediawikistaging/phase3/includes/GlobalFunctions.php(669): wfMsgGetKey('pagetitle', true, false, true)
#4 /usr/share/mediawikistaging/phase3/includes/GlobalFunctions.php(575): wfMsgReal('pagetitle', Array, true)
#5 /usr/share/mediawikistaging/phase3/includes/OutputPage.php(482): wfMsg('pagetitle', 'Main Page')
#6 /usr/share/mediawikistaging/phase3/includes/Article.php(818): OutputPage->setPageTitle('Main Page')
#7 /usr/share/mediawikistaging/phase3/includes/Wiki.php(499): Article->view()
#8 /usr/share/mediawikistaging/phase3/includes/Wiki.php(73): MediaWiki->performAction(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebRequest))
#9 /usr/share/mediawikistaging/phase3/index.php(116): MediaWiki->performRequestForTitle(Object(Title), Object(Article), Object(OutputPage), Object(User), Object(WebRequest))
#10 {main}

1.16alpha (r59858) was still working fine.

Version: unspecified
Severity: critical