[NTG-context] ConTeXt inputs files from TEXMF/doc

Hello, I used \externalfigure[background] in a document (and I forgot to compile the local file background.tex) and ended up with a pleasant surprise: the command included /usr/local/texlive/2012/texmf-dist/doc/latex/background/background.pdf instead of complaining that the file doesn't exist. Shouldn't ConTeXt prevent inclusion of documents from "doc"? Mojca PS: tested with ConTeXt from TeX Live (as is probably evident from the fact that the file from TL has been found).