I took care of the permissions. Now it says:

Caused by: hudson.plugins.git.GitException: Command "git tag -a -f -m Jenkins Build #13 jenkins-SqueakTrunk-13" returned status code 128:
stdout: 
stderr: 
*** Please tell me who you are.

Run

  git config --global user.email "you@example.com"
  git config --global user.name "Your Name"

to set your account's default identity.
Omit --global to set the identity only in this repository.

I did some of that and it is not yet mollified:

chriscunnington@box3-squeak:/var/lib/jenkins$ git config --global user.email "frank.shearar@gmail.com"
chriscunnington@box3-squeak:/var/lib/jenkins$ git config --global user.name "Frank Shearar"

Chris