Sometimes I find a question that was closed as a duplicate, but it does not have a reference to the source question.

How is this possible?

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Link to example (not reproduced after reopened)

Question was reopened after I say this about our CM.

Message in chat with this question was in 13.09 UTC, after that CM reopen it in 13.17, so this does not seem like cache or timing problem with reopening.

Also this revision does not exist, removing something as in linked question.

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Another example

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    If you look at that link now, the question is open, seems like it could just be a strange timing bug for when you viewed the post? ie it was reopened exactly as you loaded the page and there is a delay bettween removing the link and the box? I don't know for sure. – Mark Kirby Feb 14 '18 at 13:45
  • @MarkKirby, seems like our CM reopen this question so i just should find another sample :) – Grundy Feb 14 '18 at 13:48
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    Possible duplicate of Should users be allowed to remove the "Possible Duplicate" links on closed questions? <--- until 2013 duplicate banner was part of the question text and could be edited out – gnat Feb 14 '18 at 13:51
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    @gnat Not a duplicate of that question. This closure was done in 2015, well after that change. – Sonic the Curiouser Hedgehog Feb 14 '18 at 13:55
  • @Ano this site (ex hashcode.ru) probably used old codebase prior to joining Stack Exchange in Apr 2015 – gnat Feb 14 '18 at 13:58
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    @gnat There is no evidence in the revision history of that question of a duplicate link being added by Community and then removed. – Sonic the Curiouser Hedgehog Feb 14 '18 at 14:02
  • again, could be a matter of old codebase @Ano - it is well possible that in ancient times automatic insertion of the banner into question text at the moment of closure wasn't reflected in revisions list – gnat Feb 14 '18 at 16:11
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    @gnat But you'd still see a revision where a user removes the link. – Sonic the Curiouser Hedgehog Feb 14 '18 at 16:14

hashcode.ru ran on its own Q&A implementation (not, say, our SE 1.0), so the treatment of duplicates could've been quite different. It's also possible that this is something that just got lost in the migration from that code/database to our stack.

Nicolas, the community manager for the Russian SO site, tells me that hashcode.ru didn't have "duplicate" as a close reason at all, so I'm leaning more towards the "something went off the rails in the data import".

Ultimately, the answer to "what happened here" can be summed up as ¯\_(ツ)_/¯. Could be any number of things, with the true issue having been lost to time.

  • what you can suggest do with this? leave as is or reopen or reopen and close with another reason? – Grundy Feb 14 '18 at 20:48
  • @Grundy It's a fine thing to ask. I see no reason to close or do anything else. – Adam Lear Feb 14 '18 at 20:48
  • i mean what do with a questions that closed as duplicate without links to source :) – Grundy Feb 14 '18 at 20:53
  • @Grundy Are there a lot of these? Your post sounded like you just found the one. – Adam Lear Feb 14 '18 at 20:54
  • in answer @MSDN.WhiteKnight he found 72. Also in question was links to two – Grundy Feb 14 '18 at 20:55
  • @Grundy I'll check with Nicolas and see if he has any backups handy to see if we can figure out what happened. With such a small number of affected questions, though, I'm not super worried about it either way, to be honest. – Adam Lear Feb 14 '18 at 21:17
  • @Grundy Just to follow up... Nicolas went through that list of questions and closed/reopened/deleted as needed. – Adam Lear Feb 15 '18 at 16:57
  • Ooooooooook :-) – Grundy Feb 15 '18 at 17:57

This question was closed with close reason 1 ("exact duplicate"), which is different from usually used for new questions close reason 101 (just "duplicate"). It does not have target post id attached in revision history. See https://data.stackexchange.com/ru/query/804838

Probably in 2015 there was different mechanism of duplicates, that stored target post id somewhere else, and now it get lost. Another example

Actually, there are 72 questions closed with close reason "1", all between Jan 2015 and March 2015. After March 2015, there were no questions closed with that close reason, and instead questions were closed with correct "101" close reason. So looks like Ru SO was misconfigured in that period, allowing folks to close questions as duplicates of nothing.


Another case where this can happen is in older duplicate closures, done before a change was made to the manner in which duplicate links are displayed in questions. Before that change, the link was edited directly into the top of the question body by the Community user (without showing the edit on the question itself; you may need to manually navigate to the revision history to see the revision). That link was susceptible to being changed and even removed by anyone editing the post. After that change was made in February 2013, duplicate links show as a separate automatic notice rather than as part of the post body, so you won't see this happen with later closures.


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