python-pymysql ftbfs in focal

seen in a focal test rebuild:
https://launchpad.net/ubuntu/+archive/test-rebuild-20200810-focal/+build/19799887

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ERROR: test_issue_288 (pymysql.tests.test_basic.TestBulkInserts)
executemany should work with "insert ... on update"
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Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/pymysql/tests/test_basic.py", line 360, in test_issue_288
    cursor.executemany("""insert
  File "/<<PKGBUILDDIR>>/pymysql/cursors.py", line 195, in executemany
    return self._do_execute_many(q_prefix, q_values, q_postfix, args,
  File "/<<PKGBUILDDIR>>/pymysql/cursors.py", line 234, in _do_execute_many
    rows += self.execute(sql + postfix)
  File "/<<PKGBUILDDIR>>/pymysql/cursors.py", line 170, in execute
    result = self._query(query)
  File "/<<PKGBUILDDIR>>/pymysql/cursors.py", line 329, in _query
    self._do_get_result()
  File "/<<PKGBUILDDIR>>/pymysql/cursors.py", line 353, in _do_get_result
    self._show_warnings()
  File "/<<PKGBUILDDIR>>/pymysql/cursors.py", line 369, in _show_warnings
    warnings.warn(err.Warning(*w[1:3]), stacklevel=4)
pymysql.err.Warning: (1287, "'VALUES function' is deprecated and will be removed in a future release. Please use an alias (INSERT INTO ... VALUES (...) AS alias) and replace VALUES(col) in the ON DUPLICATE KEY UPDATE clause with alias.col instead")

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Ran 172 tests in 5.296s

FAILED (errors=1, skipped=17, expected failures=1)
No garbages!
E: pybuild pybuild:341: test: plugin custom failed with: exit code=1: debian/run_tests.sh python3.8