Don't load test env by default
Pass a base relation to build_default_scope when joining

This allows the default scope to be built using the current table alias.
Resolves #12770
Updating select helper doc [ci skip]
Fix misspelling in references docs
Update documentation on group method to indicate it takes an array

The group method also takes an array, however this isn't immediately
clear by reading the source since it delegates this method. If you
trace it back to the AREL building you can see that it does support
an array.

Shoutout to @betovelandia for pointing this out.
Mention required glob param name in match docs for mapper

THe match documentation doesn't mention any requirement of the
parameter name requirement for matches. However, including a
bare glob character without a variable assignment causes a
parse error.
create indexes inline in CREATE TABLE for MySQL

This is important, because adding an index on a temporary table after
it has been created would commit the transaction

Conflicts:
	activerecord/CHANGELOG.md
Fixes bugs for using indexes in CREATE TABLE by adding checks for table existence

Also:
  - updates tests by stubbing table_exists? method
  - adds entry for creating indexes in CREATE TABLE to changelog
link to "Schema migration" Wikipedia page. Closes #14479. [ci skip]
[ci skip] Fix Pull Request URL in 4.1 release note.
Merge pull request #14487 from JuanitoFatas/patch/fix-release-note-url

[ci skip] Fix Pull Request URL in 4.1 release note.
Merge pull request #14480 from steverice/mysql-indexes-in-create-table

Create indexes inline in CREATE TABLE for MySQL
Append link to bad code to backtrace when exception is SyntaxError
Invert the conditionals to make easier to read

Also improve some of the code conventions
Remove unneeded comments about feature support on the adapters

These comments will likely be outdated with time and doesn't include
any information that can't be found in the adapters
Improve the method

* cache `o.name` value
* Avoid extra `concat` call
* Avoid extra `<<` call
Make method private
Don't use send when we own the method
No need to gsub the string
No need to use begin/end blocks