Mabutu (aka Mobutu - I presume) is actually the Russian nickname for the Soviet 1981 TTsKO tricolor series of camouflage uniforms. Dennis Desmond notes this in his book, and I have seen at least one other reference to this nickname in a book on African military conflicts. I have always presumed it referred just to the camouflage uniforms, but the nickname may also include the khaki combat uniforms as well. There is significant evidence that Soviet advisors and security forces were operating in various parts of Africa during the 1980s, particularly in places like Angola and Mozambique. Russian uniforms ended up in the hands of Rhodesian, SW African, South African and other insurgent groups, so my guess is a uniform like this was either donated as "war aid" or was simply left by advisors. The lightweight uniform was probably a lot more comfortable in the hot African sun than the Russian BDU-style uniform.
I actually have a very nice one-piece aviator's coverall (made either in Russia or the Ukraine) that was captured by SA Special Forces in Angola.