Is there a reason to use &= rather than just = on a boolean?

I ran across some code today that was checking a number of error conditions. A single boolean was used all the way through, but instead of reassigning it every time with an =, it was reassigned with an &= resulting in a bit wise ANDing of the the previous value of the boolean and the new value. The code looked something like this:

bool result = FirstCheck();
Assert(result);
result &= SecondCheck();
Assert(result);
...

Now I'm curious why someone would do this? This is logically equivalent to just reassigning the value of the boolean as shown by the possible branches below:

1. FirstCheck fails (returns false) and program fails on assert and never makes it to SecondCheck
2. FirstCheck passes (returns true) and the program makes it to SecondCheck. If SecondCheck returns true, then result is true because true&true = true. If SecondCheck returns false, then result is false becasue true&false = false.

Since there is no logical difference, is there some other reason &= might be preferable? Or is it more likely that is is a relic of some old code that just never got changed?

EDIT: To clarify, the Assert is always active code. I actually stumbled across this code while investigating a bug because the assert was failing.