IronPython gets crashing when rebinding __repr__ as __str__

[xiaxinmeng]

IronPython interpreter crashes when rebinding __repr__ as __str__.

test.py

class Foo(object):
    pass

Foo.__repr__ = Foo.__str__

foo = Foo()
str(foo)

Crash report:

.... at IronPython.Hosting.PythonCommandLine.RunFile (string) [0x0000f] in <5cd2739cd27844619789a1aa1ffdb0b0>:0 at Microsoft.Scripting.Hosting.Shell.CommandLine.Run () [0x0003a] in <252827dbc7924637ba1c8c95b5f54810>:0 at IronPython.Hosting.PythonCommandLine.Run () [0x000d8] in <5cd2739cd27844619789a1aa1ffdb0b0>:0 at Microsoft.Scripting.Hosting.Shell.CommandLine.Run (Microsoft.Scripting.Hosting.ScriptEngine,Microsoft.Scripting.Hosting.Shell.IConsole,Microsoft.Scripting.Hosting.Shell.ConsoleOptions) [0x0003c] in <252827dbc7924637ba1c8c95b5f54810>:0 at Microsoft.Scripting.Hosting.Shell.ConsoleHost.RunCommandLine () [0x00053] in <252827dbc7924637ba1c8c95b5f54810>:0 at Microsoft.Scripting.Hosting.Shell.ConsoleHost.ExecuteInternal () [0x00051] in <252827dbc7924637ba1c8c95b5f54810>:0 at PythonConsoleHost.ExecuteInternal () [0x00025] in <9cafe2448f474c41b81ba0c1d71815eb>:0 at Microsoft.Scripting.Hosting.Shell.ConsoleHost.Execute () [0x00032] in <252827dbc7924637ba1c8c95b5f54810>:0 at Microsoft.Scripting.Hosting.Shell.ConsoleHost.Run (string[]) [0x0015b] in <252827dbc7924637ba1c8c95b5f54810>:0 at PythonConsoleHost.Main (string[]) [0x00020] in <9cafe2448f474c41b81ba0c1d71815eb>:0 at (wrapper runtime-invoke) <Module>.runtime_invoke_int_object (object,intptr,intptr,intptr) [0x0002a] in <9cafe2448f474c41b81ba0c1d71815eb>:0

System

IronPython 3.4.0a1 (3.4.0.0001) [.NETFramework,Version=v4.6 on Mono 6.12.0.122 (64-bit)] on linux