Reproducing dateutil/dateutil#1478

Reproduction script

import sys
import dateutil
from dateutil.parser import parse

CASES = [
    ("UTC-4", -14400),
    ("UTC+4", +14400),
    ("UTC-04:00", -14400),
    ("UTC+04:00", +14400),
]

observations = []
for label, expected in CASES:
    dt = parse(f"2026-03-11 14:32:45 {label}")
    actual = int(dt.utcoffset().total_seconds())
    observations.append({
        "input": label,
        "expected_offset_seconds": expected,
        "actual_offset_seconds": actual,
        "inverted": actual == -expected and actual != expected,
    })

inversions = sum(1 for o in observations if o["inverted"])

{
    "dateutil_version": dateutil.__version__,
    "python_version": sys.version.split()[0],
    "cases": observations,
    "inverted_count": inversions,
    "case_count": len(CASES),
    "reproduced": inversions == len(CASES),
}