RFR: JDK-8257539: tools/jpackage/windows/WinL10nTest.java unpack.bat failed with Exit code: 1618

[Andy Herrick]

Same code change as https://github.com/openjdk/jdk/pull/1676 that got messed up with merge

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Commit messages:
 - JDK-8257539: tools/jpackage/windows/WinL10nTest.java unpack.bat failed with Exit code: 1618

Changes: https://git.openjdk.java.net/jdk/pull/1720/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1720&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257539
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1720.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1720/head:pull/1720

PR: https://git.openjdk.java.net/jdk/pull/1720