irb.rb: update `_`

* lib/irb.rb (IRB::Irb#eval_input): update `_` after exception.
  [ruby-core:86989] [Bug #14749]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63409 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/irb.rb

@@ -439,7 +439,7 @@ module IRB
 
     # Evaluates input for this session.
     def eval_input
-      last_error = nil
+      exc = nil
 
       @scanner.set_prompt do
         |ltype, indent, continue, line_no|
@@ -490,18 +490,17 @@ module IRB
         signal_status(:IN_EVAL) do
           begin
             line.untaint
-            @context.evaluate(line, line_no, exception: last_error)
+            @context.evaluate(line, line_no, exception: exc)
             output_value if @context.echo?
-            exc = nil
           rescue Interrupt => exc
           rescue SystemExit, SignalException
             raise
           rescue Exception => exc
+          else
+            exc = nil
+            next
           end
-          if exc
-            last_error = exc
-            handle_exception(exc)
-          end
+          handle_exception(exc)
         end
       end
     end

test/irb/test_context.rb

@@ -22,6 +22,10 @@ module TestIRB
       def eof?
         @line_no >= @list.size
       end
+
+      def encoding
+        Encoding.default_external
+      end
     end
 
     def setup
@@ -49,5 +53,24 @@ module TestIRB
       assert_equal('foo', e.message)
       assert_same(e, @context.evaluate('$!', 1, exception: e))
     end
+
+    def test_eval_input
+      input = TestInputMethod.new([
+        "raise 'Foo'\n",
+        "_\n",
+        "0\n",
+        "_\n",
+      ])
+      irb = IRB::Irb.new(IRB::WorkSpace.new(Object.new), input)
+      out, err = capture_io do
+        irb.eval_input
+      end
+      assert_empty err
+      assert_pattern_list([:*, /RuntimeError \(.*Foo.*\).*\n/,
+                           :*, /#<RuntimeError: Foo>\n/,
+                           :*, /0$/,
+                           :*, /0$/,
+                           /\s*/], out)
+    end
   end
 end