I've found it by googling my time line, viewing the retweet and in the top right corner there is a down arrow - click that and it reveals a menu on which is 'copy link to tweet'. Hoping that works as it's what I've done, I couldn't find any other way in the iOS app at least.
Will give it a shot been battling with this
Did this work for you? It still shows up as the url of the original tweet haha. Ridiculous.