RFR: Improve robustness of removing invalid clones

[Robin Westberg]

Hi all,

Please review this change that improves the removal of invalid clones. The preservation is only meant to aid debugging, so any problems in that area should not throw any exception.

Best regards,
Robin

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Commits:
 - 6e03e513: Improve robustness of removing invalid clones

Changes: https://git.openjdk.java.net/skara/pull/420/files
 Webrev: https://webrevs.openjdk.java.net/skara/420/webrev.00
  Stats: 29 lines in 1 file changed: 23 ins; 4 del; 2 mod
  Patch: https://git.openjdk.java.net/skara/pull/420.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/420/head:pull/420

PR: https://git.openjdk.java.net/skara/pull/420