sort/selected rows reset while using PreventUpdate exception on callback #73

When using table and PreventUpdate exception on a callback, although the table data is not changed as expected by raising PreventUpdate , table sort/selected indexes seem to reset.

Checked the periodic http call for the interval component, seem to return expected 204/no content response, but still triggering table filter/sort/selections

related threads:
plotly/dash#190
#64

http response:
HTTP/1.0 204 NO CONTENT
Content-Type: text/html; charset=utf-8
Content-Length: 0
Server: Werkzeug/0.14.1 Python/3.6.3
Date: Mon, 11 Jun 2018 08:52:27 GMT

http request:
{"output":{"id":"datatable-simple","property":"rows"},"inputs":[{"id":"my-interval","property":"n_intervals","value":538}]}

app
import datetime
import sys
import pandas as pd

app = dash.Dash()

DF_SIMPLE = pd.DataFrame({
'x': ['A', 'B', 'C', 'D', 'E', 'F'],
'y': [4, 3, 1, 2, 3, 6],
'z': ['a', 'b', 'c', 'a', 'b', 'c']
})

app.layout = html.Div([
html.H4('DataTable Sample',id="app_title"),
dt.DataTable(
rows=DF_SIMPLE.to_dict('records'),id='datatable-simple'
),
dcc.Interval(id='my-interval', interval=5000),
], className="container")

app.css.append_css({
'external_url': 'https://codepen.io/chriddyp/pen/bWLwgP.css'
})

@app.callback(
Output('datatable-simple', 'rows'),
[Input('my-interval', 'n_intervals')])
def update_table(n):
print("Checking...")
raise dash.exceptions.PreventUpdate("No data changed!")