What are mannequins?
GitHub Enterprise Importer を使って移行を実行した後、移行されたリポジトリでのすべてのユーザー アクティビティ (Git コミットを除く) は、マネキンと呼ばれるプレースホルダー ID に帰属します。
Each mannequin only has a display name, which comes from the display name in the source repository. Mannequins do not have organization membership or repository access. Mannequins always use the same avatar, a ghost octocat, and include a mannequin label following the display name.

Reclaiming is optional and can happen any time after a migration is finished. For this reason, you can allow your team to begin working in migrated repositories before reclaiming.
Authorship for Git commits is not associated with mannequins and cannot be attributed to GitHub users by reclaiming mannequins. Instead, commit authorship is attributed to user accounts on GitHub based on the email address that was used to author the commit in Git.
How can I reclaim mannequins?
GitHub CLI を使用して、またはブラウザーで、各マネキンの履歴を組織メンバーに再属性付けできます。 GitHub CLI を使用する場合は、マネキンを一括で回収できます。 For instructions, see GitHub Enterprise Importer のマネキンの回収.
By default, reclaiming a mannequin will send an attribution invitation to the target user. The target user can choose to accept or reject the invitation.
After a user accepts an attribution invitation, all contributions previously attributed to the mannequin will be attributed to the user instead. In future migrations to the same organization, any contributions from the same mannequin will be automatically reclaimed for the same user.
If your organization uses Enterprise Managed Users and you choose to reclaim mannequins with the GitHub CLI, you can optionally skip the invitation process, immediately reclaiming the mannequin without the user's approval.