RFR: SKARA-991

[Erik Joelsson]

Add 8u270 as a special case release for hgupdate-sync labeling, just like 8u260.

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Commit messages:
 - Add 8u270 as special case release

Changes: https://git.openjdk.java.net/skara/pull/1135/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1135&range=00
  Stats: 15 lines in 2 files changed: 14 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/1135.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1135/head:pull/1135

PR: https://git.openjdk.java.net/skara/pull/1135