con = sqlite3.connect(':memory:')
con.execute(
    """CREATE TABLE ABCD (A TEXT NOT NULL,
                                  B TEXT NOT NULL,
                                  C TEXT NOT NULL,
                                  D TEXT NOT NULL,
                                  PRIMARY KEY (A, B) ON CONFLICT IGNORE)"""
    )
pysqlite's IntegrityError: distinguish 'NOT NULL' from 'UNIQUE' violation