RFR: 8259570: (macos) tools/jpackage tests fails with 'hdiutil: couldn't eject "disk2" - Resource busy'

[Alexander Matveev]

We did not able to run "hdiutil convert" due to hdiutil did not able to acquire lock on DMG image file. In this condition we got "Resource busy" from "hdiutil detach" and on repeated attempt we was getting "File Not Found" error. According to some research "Resource Busy" is normal error message for "hdiutil detach" and can happen, but it should go away soon assuming nothing else is broken. I think due to we using "-force" flag we still ejected DMG image and left system in bad stage. After re-fixing repeated detach with force this issue is not longer reproducible. I still left code for forced detach if we did not able to detach it. Also, I added work around (in case we had to do forced detach) is to convert copy of original DMG image. This work around seems to solves problem as well when hdiutil cannot acquire lock on file. I also fixed in same way detach in our test helper.

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Commit messages:
 - 8259570: (macos) tools/jpackage tests fails with 'hdiutil: couldn't eject disk2 - Resource busy'

Changes: https://git.openjdk.java.net/jdk/pull/2345/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2345&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259570
  Stats: 162 lines in 3 files changed: 151 ins; 1 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2345.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2345/head:pull/2345

PR: https://git.openjdk.java.net/jdk/pull/2345