output=$(notmuch search --output=messages 'tag:test_thread_tag')
test_expect_equal "$output" \
"id:87ocn0qh6d.fsf@yoom.home.cworth.org
output=$(notmuch search --output=messages 'tag:test_thread_tag')
test_expect_equal "$output" \
"id:87ocn0qh6d.fsf@yoom.home.cworth.org