[ci skip] Mention the change in nil handling for serialized attributes
in "Upgrading from Rails 3.2 to Rails 4.0"
[ci skip] Clarify the "Serialized Attributes" section

Mention that the change in nil handling for serialized attributes
affects custom coders.
[ci skip] Updated create! documentation description and added +attributes+ for rdoc
Merge pull request #16384 from tomkadwill/improved_create_documentation

[ci skip] Added +object+ and +attributes+ to create! description for rdoc
Rephrase how we explain RecordInvalid exception in the context of
`#create!` regarding validations in contrast to the behavior of
`#create`. Also describe creating multiple objects using an array of
hashes as the +attributes+ parameter. [ci skip] /cc #16384
Fixes to TestCaseTest.
Retrieve source code for the entire stack trace

Provide the ability to extract the source code of the entire exception stack
trace, not just the frame raising the error. This improves debugging
capability of the error page, especially for framework-related errors.
Update actionpack CHANGELOG
[ci skip] Changed 'first argument' to '+name+ argument'
Merge pull request #16428 from tomkadwill/activerecord_associations_name_param

[ci skip] Changed 'first argument' to '+name+ argument'
Fix typo in plugins doc
Merge pull request #16430 from guillermo/patch-1

Fix typo in plugins doc
Fix the #const_regexp's documentation [ci skip]

Originally introduced in f9086d63, the documentation of this method is
wrong as #const_regexp returns a string to easy the interpolation inside
regular expressions.
Merge pull request #16426 from tgxworld/fix_false_positive

Fixes to TestCaseTest.
Merge pull request #16427 from ryandao/full_stack_source_extract

Full stack source extract
Fixes test for Gemfile entry changes

Broken by fbe38c9e9d4fe9f82518e8ffc1d757459b0c5f1c
Merge pull request #16429 from arunagw/aa-build-fix-gemfile-spring

Fixes test for Gemfile entry changes
add a test for prepending SCRIPT_NAME to generated urls
save a hash allocation per request.
Add config option for cookies digest

You can now configure custom digest for cookies in the same way as `serializer`:

config.action_dispatch.cookies_digest = \SHA256'