RFR: checkout: simplify conversion logic

[Erik Helin]

Hi all,

please review this small patch to simplify the logic for when to update the hosted storage used by the `checkout` bot.

Thanks,
Erik

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Commit messages:
 - checkout: simplify conversion logic

Changes: https://git.openjdk.java.net/skara/pull/990/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=990&range=00
  Stats: 15 lines in 2 files changed: 2 ins; 9 del; 4 mod
  Patch: https://git.openjdk.java.net/skara/pull/990.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/990/head:pull/990

PR: https://git.openjdk.java.net/skara/pull/990