When building a query string via `url-build-query-string',
%-encode literal % characters appearing in both the keys and
the values.
* lisp/url/url-util.el (url--query-key-value-preserved-chars):
Define a new constant based on `url-query-key-value-allowed-chars'
specifying the characters that should be preserved when %-encoding
query-string keys and values.
(url-build-query-string): Use the new constant (fixes Bug#78984).
* test/lisp/url/url-util-tests.el (url-util-tests): Add a test.
5140e317b7