constant loading should be thread safe now, so lets remove this

Concurrent load interlock (rm Rack::Lock)

See 2f26f611 for more info.

Also fix Minitest constant reference.

PATH_INFO is already set, so this branch will never execute.

we were already generating a path in the previous code (it was just not
returned), so lets just use the already computed path to popluate the
PATH_INFO header

Since we only work with new instances, these ivars will not be set.

We should call the setter on `path_parameters` so that we know the hash
will only contain the values that we've set.

I'd like to put all env mutations together so we can understand how to
change this code to call `call` on the controller

Since parameters are converted to a query string, they will
automatically be turned in to strings by the query parser

non_path_parameters is used internally (it never escapes this method) so
we should be able to safely use a regular hash.

since we are serializing parameters, we don't need to do all the dup
checks on each object.

We should roundtrip the parameters through their respective encoders /
decoders so that the controller will get parameters similar to what they
actually get in a real world situation

Require yaml for time_with_zone isolation test

Same fix as 109e71d2 but after
mocha got removed in 2f28e5b6.

pass in the instance variable to start decoupling the meat of the parser
from the instance of the middleware

We will always make an assignment to the env hash and eliminate a
conditional

active_support/indifferent_access: fix not raising when default_proc does

If we only deal with proc objects, then we can eliminate type checking
in the parameter parsing middleware

Removed use of mocha in Active Support

Allow `pluralize` helper to take a locale.

We should use rack-test's upload file objects on the test side so that
we will be able to correctly generate mime blob posts in the future

We should convert request parameters to a query string, then let the
request object parse that query string.  This should give us results
that are more similar to the real-world

This is already supported in `ActiveSupport::Inflector#pluralize` and `String#pluralize`, so we just forward the locale.

Add Deserialization section on guides at ActiveJob Exception [ci skip]

We should assign parameters to the request object rather than mutate the
hash that is returned by `query_parameters` or `request_parameters`

this prevents mutations from being available globally

Instead of trying to manually clear out a request object, lets just
allocate a new one.  The rack ENV is reused and cleaned (still), but the
request object is not.