Added test

dbms/tests/queries/0_stateless/01073_bad_alter_partition.reference

+1	2020-01-02
+3	2020-01-02
+4	2020-01-02

dbms/tests/queries/0_stateless/01073_bad_alter_partition.sql

+DROP TABLE IF EXISTS merge_tree;
+CREATE TABLE merge_tree (d Date) ENGINE = MergeTree ORDER BY d PARTITION BY d;
+
+INSERT INTO merge_tree VALUES ('2020-01-02');
+SELECT 1, * FROM merge_tree;
+
+-- ALTER TABLE merge_tree DROP PARTITION 2020-01-02; -- This does not even parse
+-- SELECT 2, * FROM merge_tree;
+
+ALTER TABLE merge_tree DROP PARTITION 20200102;
+SELECT 3, * FROM merge_tree;
+
+ALTER TABLE merge_tree DROP PARTITION '20200102'; -- { serverError 38 }
+SELECT 4, * FROM merge_tree;
+
+ALTER TABLE merge_tree DROP PARTITION '2020-01-02';
+SELECT 5, * FROM merge_tree;
+
+DROP TABLE merge_tree;