The allegation is that setup is keeping open handles around...

[Robb, Sam]

>   So it looks like the package files aren't being closed
> somewhere.

Taking a look at the source, and trying to figure out
where something like this might occur, I ended up in
in install.cc, where I saw the following comment in
Installer::installOneSource():

  /* FIXME: potential leak of either *tmp or *tmp2 */

Here, it looks as if handling a compressed file leads to
a handle leak as an io_stream isn't closed.  Actually,
there appear to be a couple of places where a pointer
returned by io_stream::open() isn't being freed (where
I'm assuming that 'delete tmp' is the proper way to
deal with a pointer returned by io_stream::open()...)

-Samrobb