Also, at least to me, it's very unclear what this line is doing.  I know it's not new with this branch, and we apparently haven't adopted this specific rule, I'd suggest following this bbatsov styleguide entry with this one:
```
Favor the use of sprintf and its alias format over the fairly cryptic String#% method.
```
(in https://github.com/bbatsov/ruby-style-guide#syntax )