According to https://www.mediawiki.org/wiki/Extension_talk:LogoFunctions the {{#setlogo:}} tag no longer has any effect in [[mw;extension:LogoFunctions]] as $wgLogo is read (and the skin generated) before the tag is parsed.
This used to work before the MW1.31 upgrade, and was in use on a few Uncyclopedias including English (uncyclopedia.co) and Russian (absurdopedia.ru). It now does nothing.
The same issue applies to this trivial kludge of a script, which sets $wgLogo based on a {{#logotipo:/path/to/image.png}} tag:
<?php
# Define a setup function
$wgExtensionFunctions[] = 'wfLogotipoFunction_Setup';
# Add a hook to initialise the magic word
$wgHooks['LanguageGetMagic'][] = 'wfLogotipoFunction_Magic';
function wfLogotipoFunction_Setup() {
global $wgParser;
# Set a function hook associating the "logotipo" magic word with our function
$wgParser->setFunctionHook( 'logotipo', 'wfLogotipoFunction_Render' );
}
function wfLogotipoFunction_Magic( &$magicWords, $langCode ) {
# Add the magic word
# The first array element is case sensitive, in this case it is not case sensitive
# All remaining elements are synonyms for our parser function
$magicWords['logotipo'] = array( 0, 'logotipo' );
# unless we return true, other parser functions extensions won't get loaded.
return true;
}
function wfLogotipoFunction_Render( &$parser, $param1 = '' ) {
global $wgLogo;
# The parser function itself
# The input parameters are wikitext with templates expanded
# The output should be wikitext too
$parser ->disableCache();
$wgLogo = $param1;
return "";
}
?>