git-cinnabar chokes on pre-epoch dates

[riastradh]

#!/usr/bin/env cram

Set up an initial hgrc for non-interactive use in this script:

  $ export HGRCPATH="$(pwd)/.hgrc"
  $ cat <<EOF >$HGRCPATH
  > [ui]
  > interactive = no
  > quiet = yes
  > verbose = no
  > EOF

Create an hg repository:

  $ hg init repo.hg
  $ echo hello >repo.hg/README
  $ hg -R repo.hg commit -u alice@example.com -d "2025-12-07T22:14:51Z" -Am foo

git-cinnabar can clone it just fine:

  $ git -c fetch.prune=true clone -q hg::$(pwd)/repo.hg repo.git
  $ git -C repo.git log --graph
  * commit 40a85d90856979ac2ba4aa55a786cf3e7d1cf10f
    Author:  <alice@example.com>
    Date:   Sun Dec 7 22:14:51 2025 +0000
    
        foo

Create a changeset with a pre-epoch date:

  $ echo world >>repo.hg/README
  $ hg -R repo.hg commit -u alice@example.com -d "1969-12-31T23:59:58Z" -m bar

git-cinnabar can't handle it:

  $ git -C repo.git fetch origin
  fatal: called `Result::unwrap()` on an `Err` value: ParseIntError { kind: InvalidDigit }
  Run the command again with `git -c cinnabar.check=traceback <command>` to see the full traceback.
  error: git-remote-hg died of signal 6
  fatal: could not read ref refs/cinnabar/refs/heads/branches/default/tip
  [128]

Maybe it's not reasonable for git-cinnabar to accept such dates, but if so, at least it would be nice to fail gracefully rather than crash.