I just erroneously closed this Meta Stack Overflow question (timeline) as a duplicate of a totally unrelated question. How did that happen?
Well, I was using the Stack Exchange iOS app. I followed the link in this comment, linking to this Meta Stack Exchange question. Hey, that's the same question, but on the app, it's kinda hard to notice you're on a different site; they all look the same. I clicked the 'share' link, copied the URL to the clipboard, went back to the Meta Stack Overflow question and voted to close the question as a duplicate. In the app, you then get a popup asking for the ID or URL of the duplicate target. I pasted https://meta.stackexchange.com/q/307784/295232 and it was promptly closed (because of my support dupehammer) as a duplicate of question 307784 on Meta Stack Overflow.
This should not happen; if I paste a URL from another site, it should not try to extract a question ID from it and use it as a duplicate target. IMHO, this is a bug but if TPTB think it isn't, please consider it as a feature-request.
