SQL errors result in database being locked

[rajarshi]

Hi - very handy package!

I've been playing with it and Ive noticed that if I try to insert a duplicate node, it throws the expected IntegrityError. But after that, subsequent operations fail due to the db being locked.

Looking at atomic I think this is because the db is not being closed. I modified it to wrap it in try/finally and it seems to solve the problem.

def atomic(db_file, cursor_exec_fn):
    connection = None
    try:
        connection = sqlite3.connect(db_file)
        cursor = connection.cursor()
        cursor.execute("PRAGMA foreign_keys = TRUE;")
        results = cursor_exec_fn(cursor)
        connection.commit()        
    finally:
        if connection: 
            connection.close()
    return results