ImportError: No module named roslib

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I am having a problem running python files. Here are the 1st-3rd lines of the py file:

#!/usr/bin/env python
import roslib; roslib.load_manifest('irobot_mudd')
import rospy

Whenever I run $ sudo python ml.py (ml.py being the python file in question)- as well as any other py file importing roslib, I get the error message:

Traceback (most recent call last):
  File "ml.py", line 2, in <module>
    import roslib; roslib.load_manifest('irobot_mudd')
ImportError: No module named roslib

If I run

$ python ml.py

I get the following back:

Traceback (most recent call last):
  File "ml.py", line 4, in <module>
    import cv_bridge
ImportError: No module named cv_bridge

My setup.sh file is as follows:

export ROS_ROOT=/opt/ros/electric/ros
export PATH=${ROS_ROOT}/bin:${PATH}
export PYTHONPATH=${ROS_ROOT}/core/roslib/src:${PYTHONPATH}
export ROS_PACKAGE_PATH=/opt/ros/electric/stacks 
if [ ! "$ROS_MASTER_URI" ] ; then export ROS_MASTER_URI=http://localhost:11311 ; fi

this is what my python path looks like:

echo $PYTHONPATH 
/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:/opt/ros/electric/ros/core/roslib/src:

Here is the result of ls /opt/ros/electric/ros/core/roslib/src:

package.cpp  ros  roslib

And the result of ls /opt/ros/electric/ros/core/roslib/src/roslib/*.py is:

/opt/ros/electric/ros/core/roslib/src/roslib/exceptions.py   /opt/ros/electric/ros/core/roslib/src/roslib/params.py
/opt/ros/electric/ros/core/roslib/src/roslib/genpy.py        /opt/ros/electric/ros/core/roslib/src/roslib/resources.py
/opt/ros/electric/ros/core/roslib/src/roslib/gentools.py     /opt/ros/electric/ros/core/roslib/src/roslib/rosenv.py
/opt/ros/electric/ros/core/roslib/src/roslib/__init__.py     /opt/ros/electric/ros/core/roslib/src/roslib/roslogging.py
/opt/ros/electric/ros/core/roslib/src/roslib/launcher.py     /opt/ros/electric/ros/core/roslib/src/roslib/rospack.py
/opt/ros/electric/ros/core/roslib/src/roslib/manifestlib.py  /opt/ros/electric/ros/core/roslib/src/roslib/rostime.py
/opt/ros/electric/ros/core/roslib/src/roslib/manifest.py     /opt/ros/electric/ros/core/roslib/src/roslib/scriptutil.py
/opt/ros/electric/ros/core/roslib/src/roslib/message.py      /opt/ros/electric/ros/core/roslib/src/roslib/srvs.py
/opt/ros/electric/ros/core/roslib/src/roslib/msgs.py         /opt/ros/electric/ros/core/roslib/src/roslib/stack_manifest.py
/opt/ros/electric/ros/core/roslib/src/roslib/names.py        /opt/ros/electric/ros/core/roslib/src ...