notebook: problem with warnings module

The warnings module is behaving in unexpected ways, but only within a notebook. I’m using python 3.6.0.final.0 on windows 64 with notebook 4.4.1, jupyter_client 5.0.0, and jupyter_core 4.3.0, and ipython 5.3.0.

If I run ipython from the console and run the following code one line at a time:

import warnings
warnings.filterwarnings(action='ignore')
x = 1 + 1
warnings.resetwarnings()
x = 1 + 1

Everything runs as expected and there are no warnings displayed.

However, if I run the same code in a notebook with one line per cell, the following warning is displayed after cell 4 and again after cell 5:

C:\Anaconda\lib\json\encoder.py:199: DeprecationWarning: Interpreting naive datetime as local 2017-02-28 21:20:58.170463. Please add timezone info to timestamps.
  chunks = self.iterencode(o, _one_shot=True)

Essentially, any time after running warnings.resetwarnings() at any point in a notebook, every subsequent cell execution displays that warning message with the current timestamp.