added backtrace to pry object

lib/pry/pry_class.rb

@@ -111,7 +111,9 @@ class Pry
     initial_session_setup
 
     Pry.config.hooks.exec_hook(:when_started, target)
-    new(options).repl(target)
+    pry_instance = new(options)
+    pry_instance.backtrace = caller(1)
+    pry_instance.repl(target)
   end
 
   # An inspector that clips the output to `max_length` chars.

lib/pry/pry_instance.rb

@@ -23,6 +23,8 @@ class Pry
   attr_reader :input_array
   attr_reader :output_array
 
+  attr_accessor :backtrace
+
   # Create a new `Pry` object.
   # @param [Hash] options The optional configuration parameters.
   # @option options [#readline] :input The object to use for input.