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.