What is the proper token-attr behavior?

If I read the documentation:

"Expands to the attribute values of the current object in either the
current operation or the source data

I interpret that like this:

If the attribute is available in the operation, use it, otherwise get it
from the source.

When I test it using IDM3.5.1 or the simulator in Designer 2.1.1 trying to
set a local variable using token-attr it first generates a query to get
the source attribute. If I ignore the query in the simulator it then uses
the attribute from the operation.

<do-set-local-variable name="var-TEST">
<token-attr name="TEST"/>

A test document I used:

<?xml version="1.0" encoding="UTF-8"?><nds dtdversion="3.5"

<modify class-name="test" dest-dn="xxx" dest-entry-id="40189"
event-id="xxx" src-dn="asdad">
<modify-attr attr-name="TEST">