Fix autocorrect for SpecialGlobalVars

[nevir]

It was replacing $! with "$ERROR_INFO from English library", for example.

[bbatsov]

Nice catch. You can simplify the code a lot by simply checking if a constant is defined? - if it's not the English library should be included. That will remove the need for the use of a set the complex message generation logic. You should also update the changelog.

[nevir]

I'm not sure I follow:

• I can't use defined? as a proxy for the blacklist because rubocop requires English.
• Also, since English is just a bunch of alias calls, there doesn't appear to be a consistent way to determine whether or not a global comes from it at runtime (short of parsing the file...) :(

[nevir]

Updated the changelog

[bbatsov]

Yep, you're right. I didn't think this through.

[bbatsov]

You'll have to rebase this again.

[nevir]

good to go!