[Zope] Weird paths in the filesystem using Photo and ExtFile

[Pablo Ziliani]

Hi all,
I am experimenting some problems with Photo/Photo Folder (or ExtFile) 
products in a fresh Zope instance.
I have two different sites that share a very similar structure. Their 
virtual roots are sibling folders in the ZODB.
Both have a Photo Folder called "images", that are storing in the 
filesystem via ExtFile. The problem is that when a photo with a non-yet 
generated display is being called through the virtual url, the 
corresponding image is created in the filesystem as if the topmost 
folder was the virtual root of the site (namely 
$INSTANCE_HOME/var/photos/). If I call this photo through the "real" 
(non virtual) url, this topmost folder matches the ZODB root.

For example, if I call these "real" urls:
 - http://zopeserver.com:8080/sites/site1/images/image.jpg?display=whatever
 - http://zopeserver.com:8080/sites/site2/images/image.jpg?display=whatever

in the filesystem I would have something like:
 - $INSTANCE_HOME/var/photos/sites/site1/images/image.jpg/image_whatever.jpg
 - $INSTANCE_HOME/var/photos/sites/site1/images/image.jpg/image_whatever.jpg

but if I call the same via the virtual url:
 - http://www.virtualsite1.com/images/image.jpg?display=whatever
 - http://www.virtualsite2.com/images/image.jpg?display=whatever

I only get:
 $INSTANCE_HOME/var/photos/images/image.jpg/image_whatever.jpg

both paths point to the same file! I think you understand why this 
worries me.
Any hint would be greatly appreciated.

Thanks,
Pablo

Relevant software installed:
    Linux Fedora Core 3
    Zope: 2.9.4
    Python: 2.4.3
    ExtFile: 1.5.0-beta1
    Photo: 1.3.1


PS: and BTW, the Zipupload feature in Photo Folder fails miserably for 
some reason.