util: eliminate the possibility of returning None from `versiontuple()` This fixes the following error flagged by pytype: File "/mnt/c/Users/Matt/hg/mercurial/extensions.py", line 228, in load: unsupported operand types for > [unsupported-operands] Primitive types 'Optional[tuple]' and 'curver: Optional[tuple]' are not comparable. Differential Revision: https://phab.mercurial-scm.org/D11473

#require rustfmt test-repo

  $ . "$TESTDIR/helpers-testrepo.sh"

  $ cd "$TESTDIR"/..
  $ RUSTFMT=$(rustup which --toolchain nightly-2020-10-04 rustfmt)
  $ for f in `testrepohg files 'glob:**/*.rs'` ; do
  >   $RUSTFMT --check --edition=2018 --unstable-features --color=never $f
  > done