Folks do what folks do. Mishear, fill the gaps, customise for the moment and some are sticklers for accuracy. Folk music is a minefield for pedants. And a rich source of pedant antics.

And anyway didn't Stan Hugill say as much: shanties evolved to amuse and assist. I can remember going round the Worcester Porcelain works and the painters (all women) sang for amusement and you could hear them re-doing verses and laughing. Crude or pointed at bosses I couldn't tell. But it entertained them, and the concept alone entertained me for all of the minute, until we were shooed on. I presume the songs were popular fair known to the assemblage but the process was edifying.