RFR: 1144: Recreated tag causes HostedRepositoryPool to fail fetch

[Erik Joelsson]

This patch makes it possible to force an update of a tag in a Repository as well as forcing fetching of an updated tag. This is then used in the HostedRepositoryPool to avoid errors when a tag has been updated in a repository, which is currently preventing bots from operating on such repositories.

-------------

Commit messages:
 - SKARA-1144

Changes: https://git.openjdk.java.net/skara/pull/1210/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1210&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-1144
  Stats: 70 lines in 5 files changed: 60 ins; 0 del; 10 mod
  Patch: https://git.openjdk.java.net/skara/pull/1210.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1210/head:pull/1210

PR: https://git.openjdk.java.net/skara/pull/1210