Two articles sharing the same de number

[LizzAlice]

There should only be one article per de number, but sometimes there are multiple with the same one. Those should be merged and the unnecessary profile page deleted.

[LizzAlice]

• get all items that share a de number
• find out if all items in the result are ones where one should be the preprint of the other -> they are not
• check some items for further problems that could occur when merging
• handle items that only need to be merged
  • get subset of items that are normal duplicates of each other
  • delete profile pages for those items being merged into the other
  • execute script to merge them into each other
• handle items that have an arxiv id involved
  • case where only one of them has an arxiv id
    • get all of them
    • remove zbl id and de number from the arxiv one and add preprint_of
    • items that were skipped because of their link to a deleted profile page: Q6342300
    • do another run where for the arxiv items we change the description to remove the de number
  • case where both have an arxiv id -> fix manually
• check if there are still leftover cases

[LizzAlice]

Different causes:

- Duplicated items, this only was possible because the earlier one did not have the de number in the description; no arxiv id: Q5970746 and Q2065277 -> these should be merged
- different arxiv ids, same de number and zbl id; one was from the arxiv importer, the other one from the zbmath importer -> remove de number and zbl id from item made by arxiv import and set it as preprint of zbmath item, remove arxiv id from item by zbmath importer: Q894209, Q6240347
- one of them has no arxiv id but the other one does have one and a de number and zbl id; both of them have de number in the title, but one of them with ";", which is how it could be saved: Q2105143, Q6342296
- items are both the same but the titles are different, which is how they could be saved: Q2197040, Q6483661 -> these should be merged
- I have no idea how these items could be saved, title and description seem to be identical: Q2929805, Q6486636 -> they should be merged