ComponentWillUnmount should only ever be invoked once

src/renderers/shared/reconciler/ReactCompositeComponent.js

@@ -132,6 +132,9 @@ var ReactCompositeComponentMixin = {
 
     // See ReactUpdates and ReactUpdateQueue.
     this._pendingCallbacks = null;
+
+    // ComponentWillUnmount shall only be called once
+    this.calledComponentWillUnmount = false;
   },
 
   /**
@@ -405,7 +408,8 @@ var ReactCompositeComponentMixin = {
     }
     var inst = this._instance;
 
-    if (inst.componentWillUnmount) {
+    if (inst.componentWillUnmount && !inst.calledComponentWillUnmount) {
+      inst.calledComponentWillUnmount = true;
       if (safely) {
         var name = this.getName() + '.componentWillUnmount()';
         ReactErrorUtils.invokeGuardedCallback(name, inst.componentWillUnmount.bind(inst));

src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js

@@ -1303,4 +1303,38 @@ describe('ReactCompositeComponent', function() {
 
   });
 
+  it('should only call componentWillUnmount once', function() {
+    var app;
+    var stage = 1;
+    var count = 0;
+
+    class App extends React.Component {
+      render() {
+        if(stage === 1) return <UnunmountableComponent />;
+        else return null;
+      }
+    }
+
+    class UnunmountableComponent extends React.Component {
+      componentWillUnmount() {
+        app.setState({});
+        count++;
+        throw Error('always fails');
+      }
+
+      render() {
+        return <div>Hello {this.props.name}</div>;
+      }
+    }
+
+    var container = document.createElement('div');
+
+    expect(function(){
+      ReactDOM.render(<App ref={(ref)=>{if(ref) app = ref;}} />, container);
+      stage = 2;
+      ReactDOM.render(<App ref={(ref)=>{if(ref) app = ref;}} />, container);
+    }).toThrow();
+    expect(count).toBe(1);
+  });
+
 });