To fully complete the ghost-on-removal-when-shared-thread-exists
proposal, we need to clear all ghost messages when the last active
message is removed from a thread.
---
 lib/message.cc               | 20 ++++++++++++++++++++
 test/T590-thread-breakage.sh |  6 +-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/lib/message.cc b/lib/message.cc
index 1b423b0..39dbe53 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -1098,6 +1098,26 @@ _notmuch_message_delete (notmuch_message_t *message)
 
 	notmuch_message_destroy (ghost);
 	status = COERCE_STATUS (private_status, "Error converting to ghost message");
+    } else {
+	/* the thread is empty; drop all ghost messages from it */
+	notmuch_messages_t *messages;
+	status = _notmuch_query_search_documents (query,
+						  "ghost",
+						  &messages);
+	if (status == NOTMUCH_STATUS_SUCCESS) {
+	    notmuch_status_t last_error = NOTMUCH_STATUS_SUCCESS;
+	    while (notmuch_messages_valid (messages)) {
+		message = notmuch_messages_get (messages);
+		status = _notmuch_message_delete (message);
+		if (status) /* we'll report the last failure we see;
+			     * if there is more than one failure, we
+			     * forget about previous ones */
+		    last_error = status;
+		notmuch_message_destroy (message);
+		notmuch_messages_move_to_next (messages);
+	    }
+	    status = last_error;
+	}
     }
     notmuch_query_destroy (query);
     return status;
diff --git a/test/T590-thread-breakage.sh b/test/T590-thread-breakage.sh
index 81f27db..45446b9 100755
--- a/test/T590-thread-breakage.sh
+++ b/test/T590-thread-breakage.sh
@@ -121,10 +121,6 @@ notmuch new >/dev/null
 test_thread_count 0 'All messages gone: no threads'
 test_content_count apple 0
 test_content_count banana 0
-test_begin_subtest 'No ghosts should remain after full thread deletion'
-# this is known to fail; we are leaking ghost messages deliberately
-test_subtest_known_broken
-ghosts=$(../ghost-report ${MAIL_DIR}/.notmuch/xapian)
-test_expect_equal "$ghosts" "0"
+test_ghost_count 0 'No ghosts should remain after full thread deletion'
 
 test_done
-- 
2.8.0.rc3