[skara] RFR: Avoid expensive operations when comparing commit command work items

[Robin Westberg]

Ensure that the concurrentWith operation does not perform any operations that may require API call.

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Commit messages:
 - Avoid expensive operations when comparing commit command work items

Changes: https://git.openjdk.java.net/skara/pull/1030/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1030&range=00
  Stats: 11 lines in 2 files changed: 0 ins; 7 del; 4 mod
  Patch: https://git.openjdk.java.net/skara/pull/1030.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1030/head:pull/1030

PR: https://git.openjdk.java.net/skara/pull/1030