We gave you a link to download the image from, where it's clearly indicated OE2.0 or OE1.6, this from the original dreambox repository of images. Try with these.

About the answer, there is no clear indication on the images if there is no indication of OEX.X on them... that's the issue. To find out you should try to install the plugin.

Python version should be the hint for you, but you need first to install the image... to see it. But I would bet that for the DM7020HDvX most images are OE2.0.

TS
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DM8000, DM800se, DM500HD, DM800HD, DM7025, DM7020s, DM7000, DM500s
VU+ Solo, VU+ Uno, VU+ Duo, Kathrein UFS910
Tivusat, TNTSat, Fransat, SSR/TSR, BBC1-2-3/ITV
DE-OpenBlackHole 1.4 image : http://www.openblackhole.com/