Merging Gerrit identities

Basically, following https://ovirt-infra-docs.readthedocs.io/en/latest/General/Gerrit_account_merge/index.html.

If for some reason, you don't have access to refs/meta/external-ids, you can still do it on the server directly as long as you ensure that you restore the permbits for gerrit:gerrit on the git storage.

You can extract a worktree git worktree add /tmp/external-ids refs/meta/external-ids, generate a commit that fixes things and you can complete by git update-ref refs/meta/external-ids $commit_sha1.

Note:

• that CLs under dashboard of the previous account will just disappear and won't go to the new account.
• HTTP passwords are generated under the old username (?)
• prefer always to take the account with the most changes/comments.