ruby - Calling Sinatra from Sinatra produces results different from external request

Question

Following my question here. So I am trying to do a smart redirect using this:

get "/category/:id/merge" do
    #... setting @catalog_id and category
    call env.merge("PATH_INFO" => "/catalog/#{@catalog_id}/category/#{category.id}", "REQUEST_METHOD"=>"PATCH","QUERY_STRING"=>"merge=1")
    status 200
end

But when I look in logs, I see something that is not only frustrating but also completely absurd:

# this one is from internal call
I, [2013-03-21T15:55:54.382153 #29569]  INFO -- : Processing GET /catalog/1/category/2686/merge
I, [2013-03-21T15:55:54.382239 #29569]  INFO -- : Parameters: {}
...
I, [2013-03-21T15:55:54.394992 #29569]  INFO -- : Processing PATCH /catalog/1/category/2686
I, [2013-03-21T15:55:54.395041 #29569]  INFO -- : Parameters: {"merge"=>"1"}
I, [2013-03-21T15:55:54.395560 #29569]  INFO -- : Processed PATCH /catalog/1/category/2686?merge=1 with status code 404
I, [2013-03-21T15:55:54.395669 #29569]  INFO -- : Processed GET /catalog/1/category/2686/merge with status code 200

# this one is a direct request
I, [2013-03-21T15:56:36.246535 #29588]  INFO -- : Processing PATCH /catalog/1/category/2686
I, [2013-03-21T15:56:36.246629 #29588]  INFO -- : Parameters: {"merge"=>"1"}
...
I, [2013-03-21T15:56:36.286216 #29588]  INFO -- : Processed PATCH /catalog/1/category/2686?merge=1 with status code 204

And the body of internal 404 request is just Sinatra's standard 404 error page. How the hell can he tell me straight in the eye that he doesn't know this route if I caught him serving exactly the same URL with acceptable 204?

UPDATE It gets even more exciting when I change REQUEST_METHOD to GET - works like a charm.

I, [2013-03-21T17:09:37.718756 #3141]  INFO -- : Processing GET /catalog/1/category/2686/merge
I, [2013-03-21T17:09:37.718838 #3141]  INFO -- : Parameters: {}
...
I, [2013-03-21T17:09:37.735632 #3141]  INFO -- : Processing GET /catalog/1/category/2686
I, [2013-03-21T17:09:37.735678 #3141]  INFO -- : Parameters: {"merge"=>"1"}
...
I, [2013-03-21T17:09:37.773033 #3141]  INFO -- : Processed GET /catalog/1/category/2686?merge=1 with status code 200
I, [2013-03-21T17:09:37.773143 #3141]  INFO -- : Processed GET /catalog/1/category/2686/merge with status code 200