I see that one spot, that appears to have a bit of sheen to it. That's the only spot though, with all the other shapes looking too dark compared to the tones in the rest of the photo.
I am certainly not an expert at all on Communist Era Yugo uniforms and such, but I suspect this photo may not be what it is billed as in Borsarello's book. For one, he's armed with a Mauser. That's not Earth shattering, as Yugoslavia produced their own version. However, generally when Warsaw Pact countries released propoganda photos, the troops depicted were equiped with the latest and greatest "look how well our troops are outfitted you imperialist pigs" weapons and kit. So, this could be a photo from the 1940's or 50's before the introduction of the AK. In which case, we have to ask "When did Yugoslavia introduce it's first camouflage pattern"? I personally don't know.
To add, the individual in the photo looks rather full-faced and more elderly than the stereotypical youthful, strapping, well equiped Eastern Bloc border guard. Especially for a photo that was released to the West. I'm more inclined to think this is a photo of a reservist, which during the Communist era may or may not have been issued camouflage.
Again, this is all just some guessing on my part, but I do feel that the dark portions of that pattern have been inked-in for whatever reason.
Maybe someone knows of some legitimate pictures of Yugoslavian Border Guards through the years?