In 80559a94 ("zodbdump: support --pretty option with a format to show
pickles disassembly") we added support for zodbdump --pretty and
adjusted files in testdata/ to be named like 1.zdump.{raw,zpickledis}.ok
instead of just 1.zdump.ok. However, that renaming and
generation of 1.zdump.zpickledis.ok, it seems, were done by hand, because
rerunning gen_testdata.py still regenerates old 1.zdump.ok. It seems
that during nexedi/zodbtools!22 I
missed that gen_testdata.py was not updated.

-> Fix it.

Running gen_testdata.py with py2 and ZODB 5.8.1 regenerates *.fs and
*.ok files in testdata/ in exactly the same state they were.

/reviewed-by @jerome
/reviewed-on nexedi/zodbtools!24