If you have a page like

    \[[!if test="enabled(smileys)" then=":-P"]]

then enabling or disabling the smileys plugin will not rebuild it.

Unfortunately, I can't think of a good way to solve this without
introducing a special case for `enabled()` in Render.pm, either a
new dependency type `"enabled(smileys)" => $DEPENDS_ENABLED`
or a special case that treats `"enabled(smileys)" => $DEPENDS_PRESENCE`
differently. --[[smcv]]