Pendulum DST issue

pendulum.py

import pendulum

tz = pendulum.timezone('America/Los_Angeles')
start_time = pendulum.parse('2018-03-11 09:00:00+00:00')
end_time = pendulum.parse('2018-03-11 10:00:00+00:00')
print((end_time - start_time).in_hours())     # 1
print((end_time.in_tz(tz) - start_time).in_hours())  # 1
print((end_time - start_time.in_tz(tz)).in_hours())  # 1
print((end_time.in_tz(tz) - start_time.in_tz(tz)).in_hours())  # 1

p1 = (end_time - start_time).in_hours()
print(start_time.add(hours=p1) == end_time)   # True
print(p1)  # 1.0

p2 = (end_time.in_tz(tz) - start_time.in_tz(tz)).in_hours()
print(start_time.add(hours=p2) == end_time)  # True
print(p2)  # 1.0