I've cleaned the workspace and then this happened:

00:00:00.000 Started by user anonymous
00:00:00.002 Building remotely on build01-win7 in workspace V:\Jenkins\workspace\zetbox.Workflow-develop-update-nuget
00:00:00.027 Pruning obsolete local branches
00:00:00.069 FATAL: Command "config --get remote.origin.url" returned status code 1:
00:00:00.069 stdout:
00:00:00.069 stderr:
00:00:00.070 hudson.plugins.git.GitException: Command "config --get remote.origin.url" returned status code 1:
00:00:00.070 stdout:
00:00:00.070 stderr:
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:981)
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:961)
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:957)
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommand(CliGitAPIImpl.java:877)
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommand(CliGitAPIImpl.java:887)
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.getRemoteUrl(CliGitAPIImpl.java:615)
00:00:00.070 at hudson.plugins.git.GitAPI.getRemoteUrl(GitAPI.java:61)
00:00:00.070 at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.prune(CliGitAPIImpl.java:405)
00:00:00.070 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
00:00:00.070 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
00:00:00.070 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
00:00:00.070 at java.lang.reflect.Method.invoke(Unknown Source)
00:00:00.070 at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:275)
00:00:00.070 at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:256)
00:00:00.070 at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:215)
00:00:00.070 at hudson.remoting.UserRequest.perform(UserRequest.java:118)
00:00:00.070 at hudson.remoting.UserRequest.perform(UserRequest.java:48)
00:00:00.070 at hudson.remoting.Request$2.run(Request.java:326)
00:00:00.070 at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
00:00:00.070 at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
00:00:00.070 at java.util.concurrent.FutureTask.run(Unknown Source)
00:00:00.070 at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
00:00:00.070 at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
00:00:00.070 at hudson.remoting.Engine$1$1.run(Engine.java:60)
00:00:00.070 at java.lang.Thread.run(Unknown Source)

The workspace stays empty.

Here's the scm config:

<scm class="hudson.plugins.git.GitSCM">
<configVersion>2</configVersion>
<userRemoteConfigs>
<hudson.plugins.git.UserRemoteConfig>
<name>origin</name>
<refspec>+refs/heads/:refs/remotes/origin/</refspec>
<url>ssh://user@example.com/path/zetbox.Workflow.git</url>
</hudson.plugins.git.UserRemoteConfig>
</userRemoteConfigs>
<branches>
<hudson.plugins.git.BranchSpec>
<name>develop</name>
</hudson.plugins.git.BranchSpec>
</branches>
<excludedUsers/>
<buildChooser class="hudson.plugins.git.util.DefaultBuildChooser"/>
<disableSubmodules>false</disableSubmodules>
<recursiveSubmodules>false</recursiveSubmodules>
<doGenerateSubmoduleConfigurations>false</doGenerateSubmoduleConfigurations>
<authorOrCommitter>false</authorOrCommitter>
<clean>true</clean>
<wipeOutWorkspace>false</wipeOutWorkspace>
<pruneBranches>true</pruneBranches>
<remotePoll>false</remotePoll>
<gitTool>Default</gitTool>
<submoduleCfg class="list"/>
<relativeTargetDir/>
<reference/>
<gitConfigName/>
<gitConfigEmail/>
<skipTag>false</skipTag>
<scmName/>
</scm>