Don't assume strings are mutable

[chocolateboy]

Avoid a FrozenError when strings are frozen globally, e.g. via --enable=frozen-string-literal.

[NorseGaud]

Hi @chocolateboy , can you write a test for this?

[chocolateboy]

I've tested it manually. You can test it automatically by adding:

# frozen_string_literal: true

to the start of every ruby file (which is recommended anyway). That way all specs test it.

[NorseGaud]

Sorry, I don't have a ruby environment anymore and really can't merge anything that doesn't have a test. Maybe one of the other maintainers of this repo can take a look. I don't think there are any other maintainers that are active for this repo :(