[PATCH 2/2] test: add known broken test for "ghost roots"

[David Bremner]

This documents the bug discussed at

     id:87efgmmysi.fsf at len.workgroup

I believe the underlying issue is that the reply to a ghost-message is
falsely classified as a root message in _resolve_thread_relationships.
---
 test/T260-thread-order.sh | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/test/T260-thread-order.sh b/test/T260-thread-order.sh
index fea61275..365ca657 100755
--- a/test/T260-thread-order.sh
+++ b/test/T260-thread-order.sh
@@ -75,4 +75,14 @@ $(for ((i = 0; i < $nthreads; i++)); do
 done
 test_expect_equal "$output" "$expected"
 
+add_email_corpus threading
+
+test_begin_subtest "reply to ghost"
+test_subtest_known_broken
+notmuch show --entire-thread=true id:mid-real-root at example.org | grep ^Subject: | head -1  > OUTPUT
+cat <<EOF > EXPECTED
+Subject: root message
+EOF
+test_expect_equal_file EXPECTED OUTPUT
+
 test_done
-- 
2.18.0