Child terms dropped from paths on node edit (using termpath-raw with any 6.x version)

Although paths using termpath-raw are initially generated correctly, upon editing a node, all terms except the first parent are dropped from the path. I have tested and confirmed this with Pathauto 6.1.1, 6.x.1.x-dev, and 6.x.2.x-dev.

To duplicate:

1.
Create a hierarchical vocabulary, such as

My vocabulary
-parent term 1
-child term 1
-child term 2

2.
Configure Pathauto to build node paths in any configuration that includes termpath-raw. For instance:
[vocab-raw]/[termpath-raw]/[title-raw]

3.
Create a node and assign parent term 1 and child term 1

4.
Path is initially generated correctly, as my-vocabulary/parent-term-1/child-term-1/node-name

5.
Edit node and save.

6.
After editing the node, the path changes to the following:
my-vocabulary/parent-term-1/node-name

Even after deleting and regenerating all node aliases, Pathauto leaves out the child term for the node in question when aliases are regenerated.