As far as I could see (and I could be wrong) this guy is wearing something with an odd top button (3 holes - they've not been used that much) and it seems to have a pattern of sorts. There's not much contrast there but the designs seem to be circles or spirals. Neither of these seem to fit with a uniform jacket. But this is something posed and professionally photographed. From that, I'd guess it was a costume of some kind or something traditional for a particular occasion (although I don't know what culture would wear patterned shirts for an occasion). The only people I can think of that would have worn dark patterned shirts at that kind of period were show cowboys (Buffalo Bill and endless lesser figures). Maybe this was the sort of thing sold at such shows although I'd expect to see a name on there somewhere.