error: You have not concluded your merge (MERGE_HEAD exists).
自分の場合は外部リポジトリ(ProofWidget4)をgit pull→conflict解決→git pull→error: You have not concluded your merge (MERGE_HEAD exists).発生
$ git reset --merge
$ git pull origin main
code:memo
PS D:\02_Area\ghworkspace\language\lean\ProofWidgets4> git pull origin main From https://github.com/EdAyers/ProofWidgets4 * branch main -> FETCH_HEAD Auto-merging lean-toolchain CONFLICT (content): Merge conflict in lean-toolchain Automatic merge failed; fix conflicts and then commit the result. 自分の場合はgit merge --abortでgit pullの内容を戻して、git reset --hard origin/mainでローカルの変更を破棄すればなんとかなった。
$ git merge --abort
$ git reset --hard origin/main
参考