Guest above wrote..."We definitely had "san francisco" in the lyric and "Navvy" was substituted with "Feller" Probably 'cos at the time "Navvy" was derogative term used for Irish immigrant workmen and even in those distant un-pc '60s they didn't want to offend. Maybe even railroad feller was the original..."
Sorry, "Railroad nigger with his hogseye" is the original, so you can see why the PC brigade changed it.
I would rather sing the original and be damned, than sing stuff cobbled up by the chicken hearted. But if I thought that my audience may be offended, I would either not sing it at all, or would explain that those were the words sung by the singers of the time, and that they were mostly "free men of colour" too.