test_cmp_rev HEAD $before
'
+test_expect_success 'root commits' '
+ git checkout --orphan unrelated &&
+ (GIT_AUTHOR_NAME="Parsnip" GIT_AUTHOR_EMAIL="root@example.com" \
+ test_commit second-root) &&
+ test_commit third-root &&
+ cat >script-from-scratch <<-\EOF &&
+ pick third-root
+ label first-branch
+ reset [new root]
+ pick second-root
+ merge first-branch # Merge the 3rd root
+ EOF
+ test_config sequence.editor \""$PWD"/replace-editor.sh\" &&
+ test_tick &&
+ git rebase -i --force --root -r &&
+ test "Parsnip" = "$(git show -s --format=%an HEAD^)" &&
+ test $(git rev-parse second-root^0) != $(git rev-parse HEAD^) &&
+ test $(git rev-parse second-root:second-root.t) = \
+ $(git rev-parse HEAD^:second-root.t) &&
+ test_cmp_graph HEAD <<-\EOF &&
+ * Merge the 3rd root
+ |\
+ | * third-root
+ * second-root
+ EOF
+
+ : fast forward if possible &&
+ before="$(git rev-parse --verify HEAD)" &&
+ test_might_fail git config --unset sequence.editor &&
+ test_tick &&
+ git rebase -i --root -r &&
+ test_cmp_rev HEAD $before
+'
+
+test_expect_success 'a "merge" into a root commit is a fast-forward' '
+ head=$(git rev-parse HEAD) &&
+ cat >script-from-scratch <<-EOF &&
+ reset [new root]
+ merge $head
+ EOF
+ test_config sequence.editor \""$PWD"/replace-editor.sh\" &&
+ test_tick &&
+ git rebase -i -r HEAD^ &&
+ test_cmp_rev HEAD $head
+'
+
+test_expect_success 'A root commit can be a cousin, treat it that way' '
+ git checkout --orphan khnum &&
+ test_commit yama &&
+ git checkout -b asherah master &&
+ test_commit shamkat &&
+ git merge --allow-unrelated-histories khnum &&
+ test_tick &&
+ git rebase -f -r HEAD^ &&
+ ! test_cmp_rev HEAD^2 khnum &&
+ test_cmp_graph HEAD^.. <<-\EOF &&
+ * Merge branch '\''khnum'\'' into asherah
+ |\
+ | * yama
+ o shamkat
+ EOF
+ test_tick &&
+ git rebase --rebase-merges=rebase-cousins HEAD^ &&
+ test_cmp_graph HEAD^.. <<-\EOF
+ * Merge branch '\''khnum'\'' into asherah
+ |\
+ | * yama
+ |/
+ o shamkat
+ EOF
+'
+
test_expect_success 'labels that are object IDs are rewritten' '
git checkout -b third B &&
test_commit I &&