trace not working with rpy2

[Larry Martell]

When I invoke my script with trace it fails with:

/usr/local/lib/python2.7/site-packages/rpy2/rinterface/__init__.py:186:
RRuntimeWarning: Fatal error: unable to open the base package

and the trace file has:

__init__.py(1):  __init__.py(19): from rpy2.robjects.robject import
RObjectMixin, RObject
cannot find system Renviron

I have tried running trace with both of these options, but I still get
the same error.

--ignore-module=rpy2
--ignore-dir=/usr/local/lib/python2.7/site-packages/rpy2

Anyone know how I can get around this error so I can use trace?