hugo server: Taxonomy pages not updated

[mkoskar]

Steps to reproduce

1. Run hugo: hugo server --disableFastRender
2. Navigate to http://localhost:1313/tags/ and note the output
3. Add tag to a content page, e.g., from tags = ['tag1'] to tags = ['tag1', 'tag2']
4. Navigate to http://localhost:1313/tags/ and refresh. The content will be the same as in step 2. while it is expected it would reflect tag2
5. Ctrl-C hugo server and restart (or run hugo build alongside`)
6. Navigate to http://localhost:1313/tags/ and refresh. Now the content is updated.

What version of Hugo are you using (hugo version)?

$ hugo version
hugo v0.146.7+extended+withdeploy linux/amd64 BuildDate=unknown

Does this issue reproduce with the latest release?

Yes

[jmooring]

git clone --single-branch -b hugo-github-issue-13648 https://github.com/jmooring/hugo-testing hugo-github-issue-13648
cd hugo-github-issue-13648
hugo server

While hugo server is running:

1. Visit the tags page
2. Add another tag to content/posts/post-1.md

Note that the tags page does not show the new tag.

[bep]

So, #13662 fixes the common problem described in here, re-rendering of e.g. /tags when new terms are added, but we still don't handle tag renames, which is a harder problem to tackle in a reasonable simple and performant way -- but that should be a less common/annoying problem. But I'll keep this issue open.