icu::Calendar::createInstance(） 泄漏内存

这是一个泄漏的测试程序（在Ubuntu 10.04，ICU 4.2上）：

#include <unicode/uversion.h>
#include <unicode/calendar.h>
int main()
{
  TimeZone* tz = TimeZone::createTimeZone("Asia/Pyongyang");
  UErrorCode status = U_ZERO_ERROR;
  Calendar* cal = Calendar::createInstance(tz, status); // adopts tz
  delete cal;
}

valgrind --leak-check=full 说：

==22978== 304 bytes in 1 blocks are possibly lost in loss record 20 of 22
==22978==    at 0x4C28F86: malloc (vg_replace_malloc.c:291)
==22978==    by 0x526B34D: icu_4_2::UnicodeString::allocate(int) (in /usr/lib/libicuuc.so.42.1)
==22978==    by 0x526B993: icu_4_2::UnicodeString::cloneArrayIfNeeded(int, int, signed char, int**, signed char) (in /usr/lib/libicuuc.so.42.1)
==22978==    by 0x526D97A: icu_4_2::UnicodeString::doReplace(int, int, unsigned short const*, int, int) (in /usr/lib/libicuuc.so.42.1)
==22978==    by 0x4EF0E90: icu_4_2::TimeZone::initDefault() (in /usr/lib/libicui18n.so.42.1)
==22978==    by 0x4EF10A4: icu_4_2::TimeZone::createDefault() (in /usr/lib/libicui18n.so.42.1)
==22978==    by 0x4EEE750: icu_4_2::GregorianCalendar::GregorianCalendar(icu_4_2::Locale const&, UErrorCode&) (in /usr/lib/libicui18n.so.42.1)
==22978==    by 0x4EEB493: ??? (in /usr/lib/libicui18n.so.42.1)
==22978==    by 0x4EEBA01: icu_4_2::Calendar::createInstance(icu_4_2::TimeZone*, icu_4_2::Locale const&, UErrorCode&) (in /usr/lib/libicui18n.so.42.1)
==22978==    by 0x400A42: icu_4_2::Calendar::createInstance(icu_4_2::TimeZone*, UErrorCode&) (in /home/jzwinck/test/a.out)
==22978==    by 0x4009C5: main

我的问题是，我是否错误地使用了 ICU，或者是否可以应用一些解决方法来释放 ICU 似乎正在创建的默认时区对象？ 我无法轻松更改正在使用的操作系统和 ICU 版本。