If you have stub display enabled, then links to stubs that include anchor links,
e.g. [[Foo#Bar]], render as a link to just [.../wiki/Foo]. With stub display
turned off, or for articles over the stub display threshold, is renders
correctly as [.../wiki/Foo#Bar]. See URL for example of [[February 29#Births]].
(I only noticed it because my stub threshold is set very high at the moment -
presumably there aren't many cases where one would need to link to a section of
a stub :)