Added test.

dbms/tests/integration/test_union_header/configs/remote_servers.xml

+<yandex>
+    <remote_servers>
+        <two_shards>
+            <shard>
+                <replica>
+                    <host>node1</host>
+                    <port>9000</port>
+                </replica>
+            </shard>
+            <shard>
+                <replica>
+                    <host>node2</host>
+                    <port>9000</port>
+                </replica>
+            </shard>
+        </two_shards>
+    </remote_servers>
+</yandex>

dbms/tests/integration/test_union_header/test.py

+import pytest
+
+from helpers.cluster import ClickHouseCluster
+
+cluster = ClickHouseCluster(__file__)
+
+node1 = cluster.add_instance('node1', main_configs=['configs/remote_servers.xml'], with_zookeeper=True)
+node2 = cluster.add_instance('node2', main_configs=['configs/remote_servers.xml'], with_zookeeper=True)
+
+
+@pytest.fixture(scope="module")
+def started_cluster():
+    try:
+        cluster.start()
+
+        for node in (node1, node2):
+
+            node.query('''
+            CREATE TABLE default.t1_local
+            (
+                event_date Date DEFAULT toDate(event_time),
+                event_time DateTime,
+                log_type UInt32,
+                account_id String
+            )
+            ENGINE = MergeTree(event_date, (event_time, account_id), 8192);
+            ''')
+
+            node.query('''
+            CREATE TABLE default.t1 AS default.t1_local
+            ENGINE = Distributed('two_shards', 'default', 't1_local', rand());
+            ''')
+
+        yield cluster
+
+    finally:
+        cluster.shutdown()
+
+
+def test_read(started_cluster):
+    assert node1.query('''SELECT event_date, event_time, log_type
+                        FROM default.t1
+                        WHERE (log_type = 30305) AND (account_id = '111111')
+                        LIMIT 1''').strip() == ''