Mark _prefix as nodoc

These methods are private API.
Follow the documentation guideline
Refactoring the code to make consitional return explicit
Following documentation guideline
We need an explicit return

If we don't return early Ruby will memoize the value of the prefix of
the parent class what will make the subsequent searchs to not work as
expected.

If the early return we are avoiding the memoization.

But when using the deprecated path we need to memoize the value, so we
are not using early return for the deprecated path.
Update Redcarpet to 3.1.2

This version fixes an API breakage between 3.0 and 3.1 ; the header
method's arity should not have changed.

[ci skip]
[ci skip]add updated information, ref[#522c0fd]
Merge pull request #15096 from robin850/patch-20

Update Redcarpet to 3.1.2
Merge pull request #15108 from arthurnn/i18n_master

Use i18n master to run tests
Merge pull request #15074 from kuldeepaggarwal/docs-changes

Add missing information, ref[#522c0fd]
remove warning `ambiguous first argument; put parentheses or even spaces`
Merge pull request #15110 from kuldeepaggarwal/fix-warning

remove warning `ambiguous first argument; put parentheses or even spaces`
Fixed a problem where `sum`, `size`, `average`, `minimum` and `maximum` used
with a grouping was not returning a Hash.
rake, remove frontbase related tasks from Active Record Rakefile.
Merge pull request #15070 from ayamomiji/sse-patch

Add multiple lines message support for SSE module
Merge pull request #14137 from dasch/better-fragment-cache-instrumentation

Add controller and action name to the fragment caching instrumentation payload

Conflicts:
	actionpack/CHANGELOG.md
Make filter_binds filter out symbols that are equal to strings

ActiveRecord::Relation::Merger's filter_binds method does not filter out bind
variables when one of the attribute nodes has a string name, but the other has
a symbol name, even when those names are actually equal.

This can result in there being more bind variables than placeholders in the
generated SQL.  This is particularly an issue for PostgreSQL, where this is
treated as an error.

This patch changes the filter_binds method to make it convert both attribute
names to strings before comparing.
Merge pull request #15078 from nbudin/fix_merger_filter_binds_comparison_master

Make filter_binds filter out symbols that are equal to strings

Conflicts:
	activerecord/CHANGELOG.md
Merge pull request #14871 from kassio/kb-fixes-namespaced-habtm

Fix how to compute class name on habtm namespaced.

Conflicts:
	activerecord/CHANGELOG.md
Don't use Active Support where it is not needed.

parent_name is a string of nil, never a blank string so we don't need to
use presence.