org-open-file with xdg-open not working?

[Eric Abrahamsen <eric@ericabrahamsen.net>]

I'm trying to open files externally (via org-attach), with a mailcap
that funnels most everything to xdg-open. I notice that doing this with
org-open-file gives me:

Running xdg-open /home/me/path/to/file.PDF...done

But no actual open file.

Doing a similar thing in gnus, with the `gnus-mime-view-part-externally'
command, gives me a similar message about xdg-open, but then the file
actually opens.

Presumably that's because the gnus version (eventually
`mm-display-external') calls xdg-open with `call-process' and org does
it with `start-process-shell-command'. The first is synchronous, the
second asynchronous, and I do remember seeing something on one of these
lists about difficulties with xdg-open because the process returns
before the file actually opens, or *doesn't* return, or some similar
thing the details of which I'm forgetting.

Have other people run into this difficulty? How are you solving it?

Thanks!
Eric