gnus-display-mime-function undefined -- resolved!

[Hrvoje Niksic <hniksic@srce.hr>]

I've hunted down a weird bug that has been reported but not explained
before.  Scenario is like this:

    Start Gnus, enter a group with RET, and search for something --
    say `multipart' -- with `M-s'.  I often do this to test Gnus MIME
    thingies.  Now, when you find a multipart article, press `g' to
    render it.

At this point, I get the "gnus-display-mime-function undefined" error, 
which appears impossible, because all of gnus-art is loaded, and the
variable is clearly defined in that file.

What really happens is that `M-s' binds the variable to nil, and
gnus-art is loaded *within that let*.  So when let finishes, the
variable returns to its previous state, i.e. to being unbound.

This example is quite scary, since it proves that you have to be very
careful about binding variables also defined in other files that are
autoloaded at various inopportune moments.  The scary part is that the
buggy code looks quite innocuous, and yet it can mulfunction is some
rarely repeated circumstances.

-- 
Hrvoje Niksic <hniksic@srce.hr> | Student at FER Zagreb, Croatia
--------------------------------+--------------------------------
Lost in Static 18 / And the storm is closing in now