Acabei de terminar o tutorial básico do Flask (aqui) e mesmo que eu tenha concluído todas as etapas, quando estou tentando

python flaskr.py

o que eu ganho é um404 Not Found erro dizendo

The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.

aqui está o código dentro do arquivo

import os
import sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, render_template, flash

#create app
app = Flask(__name__)
app.config.from_object(__name__)

#load default conf and override config from an env var
app.config.update(dict(
    DATABASE=os.path.join(app.root_path, 'flaskr.db'),
    DEBUG=True,
    SECRET_KEY = 'dev key',
    USERNAME = 'admin',
    PASSWORD = 'admin'
))
app.config.from_envvar('FLASKR_SETTINGS', silent=True)

def connect_db():
    """connect to the specific db"""
    rv = sqlite3.connect(app.config['DATABASE'])
    rv.row_factory = sqlite3.Row
    return rv

if __name__== '__main__':
    app.run()


def get_db():
    """opens a new db connection if there is none yet for the cyrrent app"""
    if not hasattr(g, 'sqlite_db'):
        g.sqlite_db = connect_db()
        return g.sqlite_db

@app.teardown_appcontext
def close_db(error):
    """closes the db again at the end of the request."""
if hasattr(g, 'sqlite_db'):
    g.sqlite_db.close()

def init_db():
    with app.app_context():
        db = get_db()
        with app.open_resource('schema.sql', mode='r') as f:
            db.cursor().executescript(f.read())
        db.commit()


@app.route('/')
def show_entries():
    db_get_db()
    cur = db.execute('select title, text from entries order by id desc')
    entries = cur.fetchall()
    return render_template('show_entries.html', entries=entries)

@app.route('/add', methods=['POST'])
def add_entry():
    if not session.get('logged_in'):
        abort(401)
    db = get_db()
    db.execute('insert into entries (title, text) values (?,?)',
        [request.form['title'], request.form['text']])
    db.commit()
    flash('New entry was successfully posted')
    return redirect(url_for('show_entries'))

@app.route('/login', methods=['GET', 'POST'])
def login():
    error = None
    if request.method == 'POST':
        if request.form['username'] != app.config['USERNAME']:
            error = 'Invalid username'
        elif request.form['password'] != app.config['PASSWORD']:
            error = 'Invalid password'
        else:
            session['logged_in'] = True
            flash('You were logged in')
            return redirect(url_for('show_entries'))
    return render_template('login.html', error=error)

@app.route('/logout')
def logout():
    session.pop('logged_in', None)
    flash('You were logged out')
    return redirect(url_for('show_entries'))

Esta é a mensagem do console que recebo (mais três tentativas para atualizar a página):

user@user:~/Flask/flaskr$ python flaskr.py
 * Running on http://127.0.0.1:5000/
 * Restarting with reloader
127.0.0.1 - - [19/Aug/2014 15:23:40] "GET / HTTP/1.1" 404 -
127.0.0.1 - - [19/Aug/2014 15:23:41] "GET / HTTP/1.1" 404 -
127.0.0.1 - - [19/Aug/2014 15:23:42] "GET / HTTP/1.1" 404 -

Alguma sugestão sobre o que pode estar errado?