title: Jenkins + git: "tell me who you are" error, why does it need to tag?
body: <p>Just installed Jenkins in Ubuntu 12.04 and I wanted to create a simple build that just clones a project and builds it.</p>
  
  <p>It fails because it cannot tag. It cannot tag because it errors out saying "<strong>tell me who you are</strong>" apparently because I didn't set git settings UserName and UserEmail.</p>
  
  <p>But, I should not need to set those, Jenkins is going to just clone the repository, why does it need the credentials if it's not going to push changes, why does it need to do a tag at all?</p>
  
  <p>Full error log is:</p>
  
  <pre><code>Started by user anonymous
  Checkout:workspace / /var/lib/jenkins/jobs/Foo.Bar.Baz/workspace - hudson.remoting.LocalChannel@38e609c9
  Using strategy: Default
  Cloning the remote Git repository
  Cloning repository origin
  Fetching upstream changes from git@mygithost.mydomain.local:foo-bar-baz/foo-bar-baz.git
  Seen branch in repository origin/1.0
  Seen branch in repository origin/1.5.4
  Seen branch in repository origin/HEAD
  Seen branch in repository origin/master
  Commencing build of Revision 479d37776b46283a946dd395c1ea78f18c0b97c7 (origin/1.0)
  Checking out Revision 479d37776b46283a946dd395c1ea78f18c0b97c7 (origin/1.0)
  FATAL: Could not apply tag jenkins-Foo.Bar.Baz-2
  hudson.plugins.git.GitException: Could not apply tag jenkins-Foo.Bar.Baz-2
  at hudson.plugins.git.GitAPI.tag(GitAPI.java:737)
  at hudson.plugins.git.GitSCM$4.invoke(GitSCM.java:1320)
  at hudson.plugins.git.GitSCM$4.invoke(GitSCM.java:1268)
  at hudson.FilePath.act(FilePath.java:758)
  at hudson.FilePath.act(FilePath.java:740)
  at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1268)
  at hudson.model.AbstractProject.checkout(AbstractProject.java:1193)
  at hudson.model.AbstractBuild$AbstractRunner.checkout(AbstractBuild.java:565)
  at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:453)
  at hudson.model.Run.run(Run.java:1376)
  at hudson.matrix.MatrixBuild.run(MatrixBuild.java:220)
  at hudson.model.ResourceController.execute(ResourceController.java:88)
  at hudson.model.Executor.run(Executor.java:175)
  at hudson.model.OneOffExecutor.run(OneOffExecutor.java:66)
  Caused by: hudson.plugins.git.GitException: Command "git tag -a -f -m Jenkins Build #2 jenkins-Foo.Bar.Baz-2" 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.
  
  fatal: empty ident  &lt;jenkins@somehostname.(none)&gt; not allowed
  
      at hudson.plugins.git.GitAPI.launchCommandIn(GitAPI.java:786)
      at hudson.plugins.git.GitAPI.launchCommand(GitAPI.java:748)
      at hudson.plugins.git.GitAPI.launchCommand(GitAPI.java:758)
      at hudson.plugins.git.GitAPI.tag(GitAPI.java:735)
      ... 13 more
  </code></pre>