Directly after logging in on wikitech I received a blank MWException page (possibly on the redirect after login?). Log in was successful, and I could use other pages
The following stack trace was retrieved by @ori
```
2015-12-03 08:41:33 silver labswiki exception ERROR: [08505f56] /w/index.php?title=Special:UserLogin&action=submitlogin&type=login&returnto=Main+Page MWException from line 220 of /srv/mediawiki/php-1.27.0-wmf.7/includes/Hooks.php: Detected bug in an extension! Hook OpenStackNovaUser::DynamicSidebarGetGroups has invalid call signature; ldap_count_entries() expects parameter 2 to be resource, boolean given {"exception_id":"08505f56"}
[Exception MWException] (/srv/mediawiki/php-1.27.0-wmf.7/includes/Hooks.php:220) Detected bug in an extension! Hook OpenStackNovaUser::DynamicSidebarGetGroups has invalid call signature; ldap_count_entries() expects parameter 2 to be resource, boolean given
#0 /srv/mediawiki/php-1.27.0-wmf.7/extensions/DynamicSidebar/DynamicSidebar.body.php(96): Hooks::run(string, array)
#1 /srv/mediawiki/php-1.27.0-wmf.7/extensions/DynamicSidebar/DynamicSidebar.body.php(21): DynamicSidebar::doGroupSidebar()
#2 [internal function]: DynamicSidebar::modifySidebar(SkinVector, array)
#3 /srv/mediawiki/php-1.27.0-wmf.7/includes/Hooks.php(204): call_user_func_array(string, array)
#4 /srv/mediawiki/php-1.27.0-wmf.7/includes/skins/Skin.php(1250): Hooks::run(string, array)
#5 /srv/mediawiki/php-1.27.0-wmf.7/includes/skins/SkinTemplate.php(461): Skin->buildSidebar()
#6 /srv/mediawiki/php-1.27.0-wmf.7/includes/skins/SkinTemplate.php(240): SkinTemplate->prepareQuickTemplate(OutputPage)
#7 /srv/mediawiki/php-1.27.0-wmf.7/includes/OutputPage.php(2319): SkinTemplate->outputPage()
#8 /srv/mediawiki/php-1.27.0-wmf.7/includes/MediaWiki.php(712): OutputPage->output()
#9 /srv/mediawiki/php-1.27.0-wmf.7/includes/MediaWiki.php(506): MediaWiki->main()
#10 /srv/mediawiki/php-1.27.0-wmf.7/index.php(43): MediaWiki->run()
#11 /srv/mediawiki/w/index.php(3): require(string)
#12 {main}
```