Fixes #67

When the script to be debugged is ruby's binary, we ignore it and pass
to byebug the script to be run by ruby instead.

lib/byebug/runner.rb

@@ -40,10 +40,13 @@ def debugged_program_from_argv
         abort
       end
 
-      prog_script = ARGV.first
-      prog_script = which(prog_script)
+      prog_script_try = which(ARGV.first)
+      if prog_script_try == which('ruby')
+        ARGV.shift
+        return which(ARGV.first)
+      end
 
-      prog_script
+      prog_script_try
     end
 
     #

test/runner_test.rb

@@ -63,10 +63,20 @@ def test_run_with_a_script_to_debug
       @runner.run
     end
 
-    def test_debugged_program_from_argv
-      ARGV.replace(%w(my_script -opt value))
+    def test_run_with_a_script_and_params_does_not_consume_script_params
+      ARGV.replace(%w(-- my_script -opt value))
+      expect_it_debugs_script
+
+      @runner.run
+      assert_equal %w(my_script -opt value), ARGV
+    end
 
-      assert_match 'my_script', @runner.debugged_program_from_argv
+    def test_run_with_ruby_script_ruby_is_ignored_and_script_passed_instead
+      ARGV.replace(%w(-- ruby ruby_script))
+      expect_it_debugs_script
+
+      @runner.run
+      assert_equal %w(ruby_script), ARGV
     end
 
     def test_run_with_no_rc_option