run sys.__interactivehook__ if it is defined

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/PythonLanguage.java

@@ -231,7 +231,7 @@ protected CallTarget parse(ParsingRequest request) throws Exception {
 
             // if we are running the interpreter, module 'site' is automatically imported
             if (source.isInteractive()) {
-                Truffle.getRuntime().createCallTarget(new TopLevelExceptionHandler(this, doParse(pythonCore, Source.newBuilder(ID, "import site", "<site import>").build()))).call();
+                runInteractiveStartup(pythonCore);
             }
         }
         RootNode root = doParse(pythonCore, source);
@@ -242,6 +242,12 @@ protected CallTarget parse(ParsingRequest request) throws Exception {
         }
     }
 
+    static final String interactiveStartup = "import site\nimport sys\ngetattr(sys, '__interactivehook__', lambda: None)()";
+
+    private void runInteractiveStartup(PythonCore pythonCore) {
+        Truffle.getRuntime().createCallTarget(new TopLevelExceptionHandler(this, doParse(pythonCore, Source.newBuilder(ID, interactiveStartup, "<site import>").build()))).call();
+    }
+
     private RootNode doParse(PythonCore pythonCore, Source source) {
         try {
             return (RootNode) pythonCore.getParser().parse(source.isInteractive() ? ParserMode.InteractiveStatement : ParserMode.File, pythonCore, source, null);