The fact that |= is a bitwise or and ||= is a logical or has a few consequences not shown in your code above. For example,

$var = 2;

$var ||= 1;  # $var now has the value 2.
$var |= 1;   # $var now has the value 3.
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One non-obvious effect that is worth mentioning is shortcut behavior. The right hand side of ||= is not evaluated if the left hand side is true. But, both sides of |= are always evaluated.

Update: Corrected term bitwise