This makes no sense (from https://gerrit.wikimedia.org/g/mediawiki/extensions/ConfirmEdit):
# cd mediawiki/extensions # git clone ssh://gerrit.wikimedia.org:29418/mediawiki/extensions/ConfirmEdit Cloning into 'ConfirmEdit'... Permission denied (publickey). fatal: Could not read from remote repository.
Please make sure you have the correct access rights and the repository exists.