Rufo modifies escape characters

[phantomwhale]

With the code:

    def regexp
      %r{
        \b            #     word boundary
        ([\w\-.])     # $1: username; first letter
        @             #     at
        ([a-z\d\-.]+) # $2: domain except TLD
        \.            #     dot
        ([a-z]+)      # $3: TLD
        \b            #     word boundary
      }xi
    end

Running rufo (0.12.0 - running on Mac / ruby 2.6.5) changes this to:

    def regexp
      %r{
        ^H            #     word boundary
        ([\w\-.])     # $1: username; first letter
        @             #     at
        ([a-z\d\-.]+) # $2: domain except TLD
        \.            #     dot
        ([a-z]+)      # $3: TLD
        ^H           #     word boundary
      }xi
    end

E.g. the \b word boundary regex matcher is interpreted as backspace and then turned into the CTRL-H (backspace) control character on completion

[gingermusketeer]

@phantomwhale I tried to reproduce this but was not able to. I wrote a test for the case you have here: https://github.com/ruby-formatter/rufo/compare/bug/regex-escape-characters?expand=1 but the tests pass in all versions of ruby.

Would you be able to do some more digging on your side? A PR with a failing test would be great.