Bug report

Bug summary

DayLocator returning incorrect times around daylights switch over, resulting in duplicate day labels.

Code for reproduction

import datetime

import pylab
import matplotlib.dates as mdates
import pytz

x = [datetime.datetime(2017, 3, 30), datetime.datetime(2017,4,4)]
y = [0, 1]

pylab.plot(x, y)

ax = pylab.gca()

tz = pytz.timezone("Australia/Sydney")
ax.xaxis.set_major_locator(mdates.DayLocator(tz=tz))
ax.xaxis.set_major_formatter(mdates.DateFormatter("%a", tz=tz))

pylab.show()

Actual outcome
The day labels for the day of the daylight switch over are duplicated, see figure below:

Expected outcome
The labels should not be duplicated.

Matplotlib version

• Operating System: Kubuntu 17.04
• Matplotlib Version: 2.02
• Python Version: Python 2.7.13
• pytz: 2017.2