The previous diff touched most files in ./test/, so bump the headers to
avoid having to touch them again for a bump later.
-BEGIN VERIFY SCRIPT-
./contrib/devtools/copyright_header.py update ./test/
-END VERIFY SCRIPT-
substitutes "for x in range(N):" by "for _ in range(N):"
indicates to the reader that a block is just repeated N times, and
that the loop counter is not used in the body