gistfile1.sh

radarek@gitmachine:/tmp/foo$ cat a.rb 
require_relative 'b'

class A
  def foo
    puts 'foo!'
  end
end

radarek@gitmachine:/tmp/foo$ cat b.rb 
class B
end

radarek@gitmachine:/tmp/foo$ pry -r ./a.rb
[1] pry(main)> edit A#foo
LoadError: cannot infer basepath
from /private/tmp/foo/a.rb:1:in `require_relative'
[2] pry(main)> RUBY_VERSION
=> "2.0.0"
[3] pry(main)> RUBY_PATCHLEVEL
=> 195
[4] pry(main)> Pry::VERSION
=> "0.9.12.2"