Hi Tom,
I do make use of the practice you have given. Normally I create a zzz-something-procs.tcl to change things that I want to change, but doesn't seem to be applicable to the general public. I guess its a fine line that I have misjudged. Normally when I see a bug, I put a patch for it. To my judgement at that time and testing, this patch will not create big changes. And I am able to patch, so I did patch it after filing on the bug tracker. Thanks for Lars for pointing this out.
Anyway I will just revert back. Although I think we need to keep the bug open. I think its a bug, maybe another solution can be more acceptable.
The backgrounder how I found this bug was. I was using ad_return_template behaviour that the same level is being used.
For example I have generic.tcl which ad_return_template to specific.tcl. I then added an optional form var, so I can override the value to specific.tcl. For example /foo/bar generic.tcl will get some vars and decide which specific.tcl it needs to return. Then I created something like this /foo/bar?usethis=value. I think I first found this when passing some optional values to a preview page. I could pass it ok, but then after the values with default of ad_return_template was not being accepted. When it actuality its being clobbered.