An unexpected success should count as an overall failure.

[Nathan Stocks]

The name states the problem. It's unexpected, meaning that's the wrong behavior. Maybe it could change.
Before:
OK (passes=4, unexpected_successes=1)
After:
FAILURE (passes=4, unexpected_successes=1)

Originally posted by @wyz23x2 in #240

[Nathan Stocks]

Fix included in 3.2.6, just released.