In the comment of this YouTube from Maribor in Slovenia, it is called an "invented song", maybe a parody of typical folk songs (love songs, hence the hilarity). However, "voro" does not seem to be a Slovenian word either. There are several Russian songs starting "Voro-, voro-", which have nothing to do with Ivanički (definitely not Russian!).

Summary: probably a panslavic joke by some choral composer / choirmaster. More information or guesswork is required.