kupu: image caching

dear developer

(silva-1.1.1)

i've replaced an image in silva with a different one but using the same 
id (using the upload feature in the edit tab of the image). i've 
deleted this image completely from silva and uploaded the new one using 
the same id.

kupu does not care and always show the old image. preview and public 
page show the correct one. again: the trusty forms editor shows the 
correct image. this seems to be some image caching bug in kupu?

regards,
marc