It does help, and prompted me to do another round of testing this morning.
I was able to reproduce the Python 3.4.2 error with Jessie Lite on a Model B Gen1 (but not on any Gen 2 or 3). I don't have a Model A or a Zero at the moment. So perhaps there is something to Jessie Lite + these stripped down models having an install failure.
That said, I was able to resolve the issue by running through this list of commands I'd posted above:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get install python3.4
sudo apt-get -f install
I had to run through them twice as on the initial run
sudo apt-get upgrade and
sudo apt-get dist-upgrade were throwing errors which were then resolved by
sudo apt-get -f install. But it was necessary to run through the commands again to exhaust the list of available packages, and ultimately grab the needed ones for Cayenne.
So if you're still seeing that "build for 3.4.2 failed" error message, try running through those commands a couple times, until you're getting output like
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. to indicate that there are no further updates available. Then attempt the Cayenne installation. It appears you don't need to do anything to clean up the previous failed installation, the installer will work past it OK.