Changing a tag name and reverting it to a previous tag name choice on
the same screen (meaning, without reloading the page) causes a 404
error.
Reproduction steps:
* Open an existing tag page https://your-discourse.com/tag/a
* Click the wrench, change the name and save
* Open edit again, revert the name to the original tag name
* 404 error
This was happening because of the way we find existing objects
in our store. Tags are using the name as the id/primary key
unlike other records in the UI. When we get the existing object
from the store we throw away the "new" ID, so we ended up with
the old tag ID on the existing object, which led to a 404. To
fix it we can just manually set the tag ID to what it is supposed
to be from params in the tag show route.
c.f.
https://meta.discourse.org/t/404-error-when-you-revert-a-tag-name-after-changing-it-without-reloading-the-page/342559
092a892a48