I am trying to import a Slack team into Mattermost, but it fails to import any users that pre-exist in the Mattermost team. It errors out on that user and does not import any posts that the user had made in Slack.
Unable to import user: <example_user>
The short term fix is to do the importing with a user that is not associated with the Slack group. However, this is not convenient for users to self-manage their own teams since all users are authenticating with an LDAP server through their Gitlab account. Is there a fix for this username collision?
I am using Mattermost 2.1.0 as part of the Gitlab 8.6.1 Omnibus package.