Incorrect rendering of unicode characters in summary buffer

[Dan Davison]

I use non-ascii characters in my summary buffer. This one renders
correctly:

  (setq gnus-sum-thread-tree-root "♽ " )

However the following render as 2 or 3 empty rectangles, followed by a
right pointing arrow (larger than the desired arrow heads):

  (setq gnus-sum-thread-tree-vertical        "│")
  (setq gnus-sum-thread-tree-leaf-with-other "├─► ")
  (setq gnus-sum-thread-tree-single-leaf     "╰─► ")

The rendering problem is present with all fonts I've tried.

However, if I use `toggle-read-only' and paste those characters into the
summary buffer, they render correctly.

How do I get my nice-looking summary buffer back?

I'm using OS X with emacs 23 and recent 24, window-system is 'ns, emacs
built using homebrew (the function `ns-toggle-fullscreen' is present and
works, I think that may imply that homebrew applied a ns fullscreen patch
during the build, or perhaps that is in emacs 24 now, I don't know.)

Thanks,

Dan