When I enter:
port select --list python
This is the result:
Available versions for python: none python25 (active)
An alternative is symlinking each and every Jupyter binary so that the version number does not appear:
cd /opt/local/bin JUPYTER_VERSION=2.7 for a in jupyter*$JUPYTER_VERSION; do sudo ln -s $a $(echo $a | sed -e 's:-'$JUPYTER_VERSION':g'); done