Military timezone parsing shows incorrect date (1 day ahead)

[sylvestre]

GNU:

  $ TZ=UTC-5 /usr/bin/date -d "B" "+%F %T %Z"
  2025-12-22 03:00:00 UTC

Rust:

$ TZ=UTC-5 ./target/debug/date -d "B" "+%F %T %Z"
2025-12-23 03:00:00 UTC

• GNU date: Shows December 22 with military timezone "B"
• Rust date: Shows December 23 (1 day ahead) with same input
• Pattern consistent across military timezones A, B, C - all show +1 day in Rust
• Times are correct (04:00, 03:00, 02:00) but date is wrong

Found with a fuzzer