It's worth noting that WMF branches also include temporary hacks to keep current
JS/CSS and cached HTML output compatible (for at least 30 days), while release branches
never contain them (and thus require HTML caches to be purged during the upgrade
This usually only affects changes to the Vector skin which is not the default there
(I'm not sure if it's even available), but nevertheless wikiHow might prefer one
of these depending on how their caching layer is set up.