Bug in Exception Message for duplicate Image names

[JensWendt]

Hello,

I just wanted to make you aware of a small bug in line 803 of populate.py.
While playing around with the script populate metadata I had a case where - unknowingly - two images were named the same.
This problem is caught in the if clause : if iname in self.images_by_name
but in the following raised Exception message:
"Image named %s(id=%d) present. (id=%s) % ( iname, self.images_by_name[iname], iid
the second format %d expects the image ID but gets an ImageI variable.
This is easily corrected by adding self.images_by_name[iname].id.val
I tried it out and now it gives the correct error message.

[will-moore]

I came across this bug while working on #62 so I have included a fix in that PR.

[JensWendt]

okay, perfect. wasn't aware. thank you