Hi,

New cop Performance/StringInclude introduced by #117 is unsafe when use with --auto-correct.

1. It currently auto-corrects the usage of match and =~. But the return values between match or =~ and include? are different. If the value is used, the behavior is altered.
2. =~ doesn't raise an error in case of nil =~ /foobar/. Same, behavior is altered.

Two examples that broke in our codebase:

search_by_street_address = params[:types] =~ /street_address/
@agenda_requested_in_config ||= method.match(/agenda/)

I think it should only fix match? and reserve match and =~ in the case of --auto-correct-all. I don't know if you can make that distinction?

If not, maybe move this cop as unsafe? What do you think?