Jython 2.7b3 weirdness

gistfile1.txt

Error in sys.excepthook:
Traceback (most recent call last):
  File "__pyclasspath__/etikettu/errorhandler.py", line 63, in exceptHook
UnboundLocalError: local variable 'traceback' referenced before assignment

Original exception was:
TypeError: canImport() takes exactly 3 arguments (2 given)

gistfile2.py

def exceptHook(type, value, traceback):
    displayError(value, traceback)

gistfile3.py

class FileTransferHandler(TransferHandler):
    def __init__(self, view):
        super(FileTransferHandler, self).__init__()
        self.view = view

    def importData(self, comp, transferable):
        for flavor in transferable.transferDataFlavors:
            if DataFlavor.javaFileListFlavor == flavor:
                fileList = transferable.getTransferData(flavor)
                self.view.processFile(fileList.get(0))
                return True
        return False

    def canImport(self, comp, transferFlavors):
        return DataFlavor.javaFileListFlavor in transferFlavors


# In other code:
panel.setTransferHandler(FileTransferHandler(self))