The fruit that the English call 'orange'
They first, from the Spanish, called 'norange'.

I have read that the Spanish 'naranja' was first transferred into English as 'a norange', and like some other words with initial 'n' had elided in oral transmission into 'an orange'. My smallish dictionary doesn't say so, but does give the derivation as from Arabic 'naranj', which would have come through the Spanish, also from the Old French 'norenge', which adds plausibility. After all we didn't go with 'oconuts, 'ananas, 'omatoes or 'otatoes. Why would we go with 'orange?

Doesn't help with the rhyme, except for the above.

There are commoner rhyme traps too, I ended a song line with 'have' ...

From memory, a most unfortunate if not inane couplet from Drink To Me Only (he sends his love a rose - now read on):

'But thou thereon didst only breathe, and and send'st it back to me
Where now I swear it looks and smells not of itself but thee'

Impossible to sing now with a straight face, especially as 'smells' is a melodic highlight.

BTW re Gundagai above, I'll leave confirmation to the more knowledgable Oz tradition keepers, but as with the many collected English folk songs gentrified for publication, I understand that the dog originally 'shat' on the tuckerbox, as only fits properly the 'final straw' sense of the lines, and the humour and language of the times.

Chris