Switching catkin workspaces carries old env vars

edit

Often I want to switch from my main catkin workspace oldws to sandbox workspace newws. But sourcing setup.bash in newws keeps adding oldws into some environment variables. As shown below, unsetting those and sourcing again doesn't help. Is there any other possible flaws??

rosman@rosmachine:~/oldws$ rm -fR build devel
rosman@rosmachine:~/newws$ rm -fR build devel
(on a new terminal)
rosman@rosmachine:~/newws$ catkin_make
rosman@rosmachine:~/newws$ source devel/setup.bash
rosman@rosmachine:~/newws$ env |grep oldws
LD_LIBRARY_PATH=~/newws/devel/lib:~/oldws/devel/lib:/opt/ros/groovy/lib
CPATH=~/newws/devel/include:~/oldws/devel/include:/opt/ros/groovy/include
PATH=~/newws/devel/bin:~/oldws/devel/bin:/opt/ros/groovy/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
PYTHONPATH=~/newws/devel/lib/python2.7/dist-packages:~/oldws/devel/lib/python2.7/dist-packages:/opt/ros/groovy/lib/python2.7/dist-packages
PKG_CONFIG_PATH=~/newws/devel/lib/pkgconfig:~/oldws/devel/lib/pkgconfig:/opt/ros/groovy/lib/pkgconfig
CMAKE_PREFIX_PATH=~/newws/devel:~/oldws/devel:/opt/ros/groovy
rosman@rosmachine:~/newws$ 
rosman@rosmachine:~/newws$ unset CMAKE_PREFIX_PATH 
rosman@rosmachine:~/newws$ unset ROS_PACKAGE_PATH 
rosman@rosmachine:~/newws$ unset CPATH 
rosman@rosmachine:~/newws$ unset LD_LIBRARY_PATH 
rosman@rosmachine:~/newws$ unset PYTHONPATH 
rosman@rosmachine:~/newws$ unset PKG_CONFIG_PATH 
rosman@rosmachine:~/newws$ env |grep oldws
PATH=~/newws/devel/bin:~/oldws/devel/bin:/opt/ros/groovy/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
rosman@rosmachine:~/newws$ source devel/setup.bash 
rosman@rosmachine:~/newws$ env |grep oldws
ROS_PACKAGE_PATH=~/newws/src:~/oldws/src:/opt/ros/groovy/share:/opt/ros/groovy/stacks
LD_LIBRARY_PATH=~/newws/devel/lib:~/oldws/devel/lib:/opt/ros/groovy/lib
CPATH=~/newws/devel/include:~/oldws/devel/include:/opt/ros/groovy/include
PATH=~/newws/devel/bin:~/oldws/devel/bin:/opt/ros/groovy/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
PYTHONPATH=~/newws/devel/lib/python2.7/dist-packages:~/oldws/devel/lib/python2.7/dist-packages:/opt/ros/groovy/lib/python2.7/dist-packages
PKG_CONFIG_PATH=~/newws/devel/lib/pkgconfig:~/oldws/devel/lib/pkgconfig:/opt/ros/groovy/lib/pkgconfig
CMAKE_PREFIX_PATH=~/newws/devel:~/oldws/devel:/opt/ros/groovy

Using Groovy on Quantal.