[Shotwell] Importing old photos that don't have EXIF

[Adam Funk <a24061 ducksburg com>]

I recently set up a new computer & started using Shotwell instead of
my mix of homebrewed photo management techniques.  I started with
an empty ~/Pictures directory and ~/Pictures.OLD copies from the old
machine's ~/Pictures.  Some of the older photos were taken with a film
camera but scanned in when I had the film developed, so they don't
have the EXIF metadata you get from a digital camera, but I've already
classified them by year and month, for example:

$ jhead ~/Pictures.OLD/2001/2001-08-France/200108-a00.jpg
File name    : /home/adam/Pictures.OLD/2001/2001-08-France/200108-a00.jpg
File size    : 848303 bytes
File date    : 2007:08:08 19:53:54
Resolution   : 2076 x 1484
JPEG Quality : 86
Comment      : LEAD Technologies Inc. V1.01?

But Shotwell falls back to the file timestamp and puts the file here:

Pictures/2007/08/08/200108-a00.jpg

Is there any way to manually override this?  At a push, I could
probably write a script to scan for photos without an exif "Date/Time"
entry & make an approximate one up, then import them, but I wonder if
there is a better way.

Thanks,
Adam