Under some condition, some code underneath `snmp` power driver
seems to call `sleep` for its own reason. That fails sleep
mock call assertion:
AssertionError: Expected 'sleep' to be called once. Called 8 times.
Calls: [call(0), call(0), call(0), ... call(0), call(5)].
This fix asserts just the sleep call we expect.
Change-Id: I2edec4cbea2d39910f1fb52b0373169c03a4ec0d