Failed to launch tasks : TypeError("Tasks must have an initial Context argument!")

[ajmalahd]

When tried to list all the task supported by trireme using inv -l, the command failed with the following stacktrace:

Traceback (most recent call last):
  File "/usr/local/bin/inv", line 11, in <module>
    sys.exit(program.run())
  File "/usr/local/lib/python2.7/dist-packages/invoke/program.py", line 286, in run
    self._parse(argv)
  File "/usr/local/lib/python2.7/dist-packages/invoke/program.py", line 352, in _parse
    self.load_collection()
  File "/usr/local/lib/python2.7/dist-packages/invoke/program.py", line 500, in load_collection
    coll = loader.load(coll_name) if coll_name else loader.load()
  File "/usr/local/lib/python2.7/dist-packages/invoke/loader.py", line 53, in load
    module = imp.load_module(name, fd, path, desc)
  File "/home/ajmal/test/migrate/tasks.py", line 2, in <module>
    from trireme import trireme
  File "/usr/local/lib/python2.7/dist-packages/trireme/trireme.py", line 4, in <module>
    from trireme.migrators import cassandra, solr
  File "/usr/local/lib/python2.7/dist-packages/trireme/migrators/cassandra.py", line 53, in <module>
    @task
  File "/usr/local/lib/python2.7/dist-packages/invoke/tasks.py", line 275, in task
    return Task(args[0], **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/invoke/tasks.py", line 61, in __init__
    self.positional = self.fill_implicit_positionals(positional)
  File "/usr/local/lib/python2.7/dist-packages/invoke/tasks.py", line 152, in fill_implicit_positionals
    args, spec_dict = self.argspec(self.body)
  File "/usr/local/lib/python2.7/dist-packages/invoke/tasks.py", line 147, in argspec
    raise TypeError("Tasks must have an initial Context argument!")

I think the error is related to a recent change in the invoke library, and can be worked around by adding a context parameter to every task function.