[dev] big issue with include_once !

[Anil Madhavapeddy]

>
> include is very, VERY incorrect - you can't define a
> class twice.

Hmm, that's what I thought initally, but it does seem to work with the
MIME_Viewer code, so I changed my mind without looking it up :-)

That does spawn drivers multiple times in the same request, since in IMP
the different MIME-parts have different driver objects associated with
them (which could be the same mime-type, and hence driver).

> And we should trap for things like the installation
> being corrupted - we need to be a lot better about error
> reporting!

Agreed.

Anil