Seeking support for patch adding "replace" to HasManyThroughAssociation

Despite documentation implying otherwise, only two out of the three
collection associations support the 'replace' (and by extension, '=')
method. The third, HasManyThroughAssociation, does not.

Fortunately, it is pretty easy to add the support. I've done that
with my patch (failing tests included) posted on this ticket:

Please take a look and consider supporting this patch.

...and we thank you for your support.

-Chris Cruft