The somewhat obfuscated usage doesn't help:

$tpl->set( 'credits', Action::factory( 'credits', $this->getWikiPage(),

						$this->getContext() )->getCredits( $wgMaxCredits, $wgShowCreditsIfMax ) );

My dev wiki is working fine though

(In reply to comment #0)

Obviously, includes/actions/CreditsAction.php has CreditsAction::getCredits(),
but I haven't tracked this down further yet.

No it doesn't, as of the revision you suggested

class CreditsAction extends FormlessAction {

public function getName() {

		return 'credits';

}

/**

• This is largely cadged from PageHistory::history *
• @return String HTML

	 */

public function onView() {

		$this->getOutput()->redirect( $this->getTitle()->getLocalURL( "action=info" ) );

}
}

/**

• Set this to the number of authors that you want to be credited below an
• article text. Set it to zero to hide the attribution block, and a negative
• number (like -1) to show all authors. Note that this will require 2-3 extra
• database hits, which can have a not insignificant impact on performance for
• large wikis. */

$wgMaxCredits = 0;

/** If there are more than $wgMaxCredits authors, show $wgMaxCredits of them.

• Otherwise, link to a separate credits page. */

$wgShowCreditsIfMax = true;

I guess you've got a max credits value of > 0

Gerrit change 26945

(In reply to comment #2)

[...]
I guess you've got a max credits value of > 0

Yes, it was set to 1. Setting it to 0 works.

(In reply to comment #1)

Obviously, includes/actions/CreditsAction.php has CreditsAction::getCredits(),
but I haven't tracked this down further yet.

No it doesn't, as of the revision you suggested
[...]

Confused two directories with different checkouts; you're right, of course.

This change also breaks the DumpHTML extension for me. It errors out with the same message:
PHP Fatal error: Call to undefined method CreditsAction::getCredits() in /srv/www/mediawiki/core/includes/SkinTemplate.php on line 339

I did a git bisect to narrow the error down to this commit. Reverting it makes DumpHTML work again. Please fix this error!

Merged by Reedy.