RFR: 8293792: runtime/Dictionary/ProtectionDomainCacheTest.java fails with FileAlreadyExistsException: /tmp

[Jie Fu]

Hi all,

runtime/Dictionary/ProtectionDomainCacheTest.java fails on Linux if `/tmp` is a symbolic link directory.
The root cause is that `JarUtils.createJarFile` [1] will throw `FileAlreadyExistsException` if `parent` is a symbolic directory.
So it seems better to test the existance of `parent` before creation.

Testing:
- tier1~3 on Linux/x64 in progress, seems fine until now

Thanks.
Best regards,
Jie


[1] https://github.com/openjdk/jdk/blob/master/test/lib/jdk/test/lib/util/JarUtils.java#L72

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Commit messages:
 - 8293792: runtime/Dictionary/ProtectionDomainCacheTest.java fails with FileAlreadyExistsException: /tmp

Changes: https://git.openjdk.org/jdk/pull/10266/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10266&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293792
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/10266.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10266/head:pull/10266

PR: https://git.openjdk.org/jdk/pull/10266