Preserve the setting of a variable when calling eager macro function.

[hs-lsong]

When running the EagerCallTag, we need to use the enterNonStackingScope instead of enterScope as the variables are in the same scope. They would have been removed if using a stacked scope. E.g.,

org.junit.ComparisonFailure: 
Expected :"{% set bar={} %}{% macro foo(bar, foobar, other) %} {% do bar.update({'a': 'b'}) %}  {{ foobar }}  {{ bar }} and {{ other }}{% endmacro %}{% call foo(bar, foobar, deferred) %} {% endcall %}{{ bar }}"
Actual   :"{% macro foo(bar, foobar, other) %} {% do bar.update({'a': 'b'} ) %}  {{ foobar }}  {{ bar }} and {{ other }}{% endmacro %}{% call foo(bar, null, deferred) %} {% endcall %}{{ bar }}"