Update pull request instructions as per the new Github UI

[ci skip]
Merge pull request #12687 from notalex/master

Update pull request instructions as per the new Github UI [ci skip]
session#fetch doesn't behave exactly like Hash#fetch.

Mention it in the changelog and add a test checking for regressions.

Hash#fetch isn't adding the defaultly returned value.
However, in the session, saving it is the behavior we should expect.

See discussion in #12692
Merge pull request #12702 from dmathieu/finetune_session_fetch

session#fetch doesn't behave exactly like Hash#fetch.
Hstore and JSON fields are not supported with store

The use of `store` on Hstore fields (for instance) is not needed
because serialization aimed to interact with Ruby objects and not
with provided field types
fix code typo in `MysqlAdapter` .Closes #12647.
no need for a CHANGELOG entry. [ci skip].
use a thread local rather than a queue so events are in the right order
Merge pull request #12203 from chancancode/eager_load_json

Eagerload active_support/json/encoding in active_support/core_ext/object/to_json
Raise an error when AS::JSON.decode is called with options

Rails 4.1 has switched away from MultiJson, and does not currently
support any options on `ActiveSupport::JSON.decode`. Passing in
unsupported options (i.e. any non-empty options hash) will now raise
an ArgumentError.

Rationale:

1. We cannot guarantee the underlying JSON parser won't change in the
   future, hence we cannot guarantee a consistent set of options the
   method could take

2. The `json` gem, which happens to be the current JSON parser, takes
   many dangerous options that is irrelevant to the purpose of AS's
   JSON decoding API

3. To reserve the options hash for future use, e.g. overriding default
   global options like ActiveSupport.parse_json_times

This change *DOES NOT* introduce any changes in the public API. The
signature of the method is still decode(json_text, options). The
difference is this method previously accepted undocumented options
which does different things when the underlying adapter changes. It
now correctly raises an ArgumentError when it encounters options that
it does not recognize (and currently it does not support any options).
Merge pull request #12214 from chancancode/json_decode_does_not_take_options

Raise an error when AS::JSON.decode is called with options
Fix release instructions

[ci skip]
:cut: whitespace
Merge branch 'master' of github.com:rails/rails

* 'master' of github.com:rails/rails:
  Fix release instructions
  Raise an error when AS::JSON.decode is called with options
  Moved all JSON core extensions into core_ext/object/json
rename AppPreparer

AppPreparer doesn't actually prepare applications, it scrubs ARGV.
Let's also get the class under test while we're at it
prepare! should return argv
stop mutating ARGV
forgot the test, oops!
test some of the rc specification
remove useless assertions