This is an issue brought up by @daniel-rikowski in rails/web-console#91.

Citing his PR proposal here:

> Prior to this, backtrace lines were simply split by a single colon.
>
> Unfortunately that is also the drive letter delimiter in Windows paths
> which resulted in a lot of empty source fragments of "C:0". ("C" from
> the drive letter and 0 from "/path/to/rails/file.rb:16".to_i)
>
> Now the trace line is split by the first colon followed by some digits,
> which works for both Windows and Unix path styles.

Now, the PR was sent against web-console, because of the templates copy
issue we used to had. Instead of bothering the contributor to reopen the
issue against upstream Rails itself, I will make sure he gets the credit
by putting his name in [rails-contributors/hard_coded_authors.rb][].

  [rails-contributors/hard_coded_authors.rb]: (https://github.com/fxn/rails-contributors/blob/master/app/models/names_manager/hard_coded_authors.rb).