I suppose if someone is taking royalties, then plagiarism could be an accurate term although "in the style of" rather than false credit, comparing the variations on here.

I suppose it's an example of the living tradition and evolution of song. I've certainly heard it as a South Yorkshire ditty with "kite" for face etc. I had to get my Collins English Dee Dah Dee Dah English phrase book out though because it meant more sense to Barnsley than the progressive advanced civilisation of south of Sheffield.

It's certainly traditional in root and there are many songs on the theme or borrowing phrases. Looking at credits isn't helpful. Just about every Ewan MaCColl song and every English and Irish tune are all bloody Irish and written by a Dubliner (take your pick) if you believe what lyric websites tell you.