RFR: 2229: TestHost propagates too many properties to backports

[Erik Duveblad]

Hi all.

please review this small patch that fixes an issue with how `TestHost` creates "backports". The problem is that the current implementation propagates too many properties from the primary issue to the backport (including for example `"issuetype"` which causes the backport to become a bug/enhancement 😄 ).

This patch also set `fixVersions` properly for the created "backport" - the `fixVersions` property is of type `Array`, not `String`.

Thanks,
Erik

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Commit messages:
 - 2229

Changes: https://git.openjdk.org/skara/pull/1633/files
  Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1633&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-2229
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/skara/pull/1633.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1633/head:pull/1633

PR: https://git.openjdk.org/skara/pull/1633