RFR: pr: update all local branches for commit comments [v2]

[Erik Helin]

> Hi all,
> 
> please review this patch that makes `CommitCommentsWorkItem` properly update all local branches prior to calling `ReadOnlyRepository.commitMetdata`. `ReadOnlyRepository.commitMetadata` is essentially `rev-list —all` for Git and all local refs need to be updated for this to work. In order to make as few networks call as possible I manually merge each local branch with its remote counterpart (instead of doing `pull`).
> 
> Testing:
> - [x] `make test` passes on Linux x64
> 
> Thanks,
> Erik

Erik Helin has updated the pull request incrementally with one additional commit since the last revision:

  No need to fetch remotes

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

Changes:
  - all: https://git.openjdk.java.net/skara/pull/1041/files
  - new: https://git.openjdk.java.net/skara/pull/1041/files/be4c8b33..ba156b91

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=skara&pr=1041&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=skara&pr=1041&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/skara/pull/1041.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1041/head:pull/1041

PR: https://git.openjdk.java.net/skara/pull/1041