Liquid templates: strange behavior when assigning variables within for loops - template-engine

Question

I'm learning Liquid (using grunt-liquid). I've run into some extremely strange behavior with a simple for loop. Perhaps you can tell me what I'm doing wrong.
Here is version 1 of my code, which works as expected:
{% assign isThree = 'initial value' %}
{% for i in (1..9) %}
{% if i == 3 %}
{% assign isThree = true %}
{% else %}
{% assign isThree = false %}
{% endif %}
<p>{{ i }}: {{ isThree }}</p>
{% endfor %}
Basically, it loops through the numbers 1 through 9, and displays each one, along with a boolean indicating whether or not the number is three. This produces the expected output:
1: false
2: false
3: true
4: false
5: false
6: false
7: false
8: false
9: false
And here's version 2 of my code, which exhibits the strange behavior in question. It's identical to version 1, except it now assigns a variable named someOtherVar before assigning isThree:
{% assign isThree = 'initial value' %}
{% for i in (1..9) %}
{% assign someOtherVar = 'foo' %}
{% if i == 3 %}
{% assign isThree = true %}
{% else %}
{% assign isThree = false %}
{% endif %}
<p>{{ i }}: {{ isThree }}</p>
{% endfor %}
This change shouldn't affect the output at all, but it does! In effect, it makes it so that values assigned to isThree aren't available until the next iteration of the loop:
1: initial value
2: false
3: false
4: true
5: false
6: false
7: false
8: false
9: false
If I move the someOtherVar assignment below the {% if %} block, then everything works fine again.
What the heck is going on here?