Rails-3.0.3 API change? Completed 406 Not Acceptable

X-posted from Ruby-on_rails Talk

Updating to Rails-3.0.3 resulted in 14 tests failing. Investigating
of them I discover that this message "Completed 406 Not Acceptable in
223ms" is being returned instead of the expected page. This error
indicates that the format of the request cannot be satisfied. Usually
format specification is html or json or pdf. Imagine my surprise then
when I see in the html generated from the view template:

<a href="/user/roles.1"

instead of:

<a href="/users/1/roles"

The question is: Why is Rails 3.0.3 asking for a format of .1 instead
requesting a user with id == 1? Is this a bug or an API change?