OSMCha incorrectly claims no tags were changed in changeset

[zabop]

I am inspecting changeset 163942334 on OSMCha. It says:

No tags were changed in this changeset.

I don't think that's true. I was the one uploading this changeset, and it is supposed to contain removal of contact:website fields which respond with a 404.

To support that this is indeed what happened in this changeset, I check Version
10 of Way 54643234, a way included in the changeset. It does not have a contact:website tag. Version 9 does. (And it says Vi fant ikke siden du lette etter, ie we don't find the page you're looking for, as expected.)

My best guess is that this is a bug. I was advised to report this here on this thread.

[jake-low]

Thanks for the detailed report @zabop. You are correct that this is a bug in OSMCha, and not a problem with your changeset. Sorry for the confusion this caused.

I believe the cause of this issue is the same as #651. The sequence is:

1. OSMCha tries to load a pre-computed diff of the changeset, but none is available (the process for building these precomputed diffs is currently pretty unreliable, see Evaluate alternatives to current Overpass instance #652 for an overview).
2. As a fallback, OSMCha tries to build a diff for the changeset using an Overpass QL query.
3. This changeset's bounding box is very large, so the query times out
4. Some parts of the UI (like the "Tag Changes" list you mentioned) don't properly anticipate this possibility, and instead of displaying an error message, they show wrong information.

Issue #651 is specifically about (3) above, but (4) is also a bug and I don't think there's an issue open to track it yet, so I'll keep this one open for that purpose.