context.rb: hide wrapping lines

* lib/irb/context.rb (IRB::Context#evaluate): separate the code
  from wrapping lines to propagate the given exception, not to show
  the wrapping lines when SyntaxError.

lib/irb/context.rb

@@ -397,7 +397,8 @@ module IRB
     def evaluate(line, line_no, exception: nil) # :nodoc:
       @line_no = line_no
       if exception
-        line = "begin ::Kernel.raise _; rescue _.class; #{line}; end"
+        line_no -= 1
+        line = "begin ::Kernel.raise _; rescue _.class\n#{line}\n""end"
         @workspace.local_variable_set(:_, exception)
       end
       set_last_value(@workspace.evaluate(self, line, irb_path, line_no))

test/irb/test_context.rb

@@ -52,6 +52,11 @@ module TestIRB
       }
       assert_equal('foo', e.message)
       assert_same(e, @context.evaluate('$!', 1, exception: e))
+      e = assert_raise(SyntaxError) {
+        @context.evaluate("1,2,3", 1, exception: e)
+      }
+      assert_match(/\A\(irb\):1:/, e.message)
+      assert_not_match(/rescue _\.class/, e.message)
     end
 
     def test_eval_input