DateUtils.parseDateWithLeniency() doesn't reset its time zone

[garydgregory]

DateUtils.parseDateWithLeniency() doesn't reset its time zone

Calendar.clear() does not reset the time zone. A previous TZ-aware pattern (for example, "z", "zz", "Z", "X..") that partially parsed could have mutated the calendar's time zone via Calendar.setTimeZone(...) before failing on the remaining tokens. Restore the caller-supplied zone for each attempt so the outcome of pattern N+1 does not depend on the partial state left by pattern N.

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