Found this one with a lucky guess.
The macro call \doiffile{picture} does find a usable picture file (I guess picture.pdf) in my tex-tree.
My conclusion would be that the search no longer starts in the current directory but does a global search first. That used to be different.
Why the change? My guess will be that Taco as Luatex's shepperd might shine some light here.

Hans van der Meer



On 4 feb. 2013, at 19:19, "H. van der Meer" <H.vanderMeer@uva.nl>
 wrote:

> Having a file picture.jpg worked fine. Now it results in inclusion of "The picture package by Heiko Oberdiek". Suddenly file searching doesn't start with the current directory anymore but somewhere in the /tex-chain.
> 
> Were the significant changes here? Something to do with Luatex? I didn't follow the developments for the last few months, so I may have missed an important change.
> 
> Hans van der Meer
> 
> 
> 
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