Fix I18n.interpolate when ActiveSupport::SafeBuffer passed as argument

[bogdan]

There could be a problem with ActiveSupport::SafeBuffer and I18n interpolate.
I've implemented a part of SafeBuffer that cause the issue in the test case.

I18n.interpolate("%{a}".html_safe, :a => 1)

By some reason $1 and $2 is not set appropriately and we have to use gsub match data instead.

[radar]

What is the use case of passing a safe buffer here? Would anyone realistically use this in their code?

[bogdan]

@radar I did. The thing is - you never know if buffer you are using is safe or not.

The example of that would be:

<%= I18n.interpolate("Get your &euro;%{amount} off".html_safe, amount: 10) %>

In my case, users are editing localizations themselves and basic HTML is allowed (like in markdown).

[radar]

Ok, that makes sense to me. Thanks @bogdan.