Right now on master the permalink editing has gone:

After git bisecting things it looks like 1f9d0b4889e5fcc8e1faa6eb446cb9355d5807de is the culprit commit. Checking into things now and trying to fix it.
We should consider adding an end-to-end test to verify that permalinks editing works as expected.
Agreed, filed #7554.
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After
git bisecting things it looks like 1f9d0b4889e5fcc8e1faa6eb446cb9355d5807de is the culprit commit. Checking into things now and trying to fix it.