Incorrect parsing of query parameters with mixed-depth nesting inside an array

Query parameters

x[y][][z]=10&x[y][][v][w]=10

(parameter order is important!)

are assembled into the params hash as

{"x"=>{"y"=>[{"v"=>{}, "z"=>"10"}]}}

instead of the correct

{"x"=>{"y"=>[{"v"=>{"w"=>"10"}, "z"=>"10"}]}}

A patch to request.rb is attached, including a new unit test that fails without the code patch.

The main bug was that on one code branch an empty hash is added to a hash_with_indifferent_access, but the standard empty hash was returned rather than the indifferent_access version of this empty hash, meaning that any updates to this hash did not go into the result hash, but into a separate hash object.

A push of the nesting stack was also missing from this code branch.