NullPointerException when renaming files

[1stone]

I'm hitting a NPE when renaming files. This is the situation:

$ git status
On branch develop
Your branch is ahead of 'origin/develop' by 21 commits.
  (use "git push" to publish your local commits)
Changes to be committed:
  (use "git reset HEAD ..." to unstage)

    renamed:    config/Custom/Old-Config.xml -> config/Configuration/New-Config.xml

Changes not staged for commit:
  (use "git add ..." to update what will be committed)
  (use "git checkout -- ..." to discard changes in working directory)

    modified:   config/Configuration/New-Config.xml

Untracked files:
  (use "git add ..." to include in what will be committed)

    config/Configuration/Test.xml

The file config/Custom/Old.xml was renamed to config/Configuration/New-Config.xml and staged.
Then, some more modifications have been made on the renamed file, but not staged yet.

When performing a git-info (org.thiesen.ant.git.ExtractGitInfo) on the repository, this exception is thrown:

build.revisioninfo.git.xml:39: java.lang.NullPointerException
    at org.thiesen.ant.git.GitInfoExtractor$NotIsGitlink.apply(GitInfoExtractor.java:76)
    at org.thiesen.ant.git.GitInfoExtractor$NotIsGitlink.apply(GitInfoExtractor.java:59)
    at com.google.common.collect.Iterators$7.computeNext(Iterators.java:603)
    at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:135)
    at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:130)
    at com.google.common.collect.Iterables.isEmpty(Iterables.java:680)
    at org.thiesen.ant.git.GitInfoExtractor.isDirty(GitInfoExtractor.java:243)
    at org.thiesen.ant.git.GitInfoExtractor.extractInfo(GitInfoExtractor.java:105)
    at org.thiesen.ant.git.ExtractGitInfo.execute(ExtractGitInfo.java:65)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.Target.execute(Target.java:392)
    at org.apache.tools.ant.Target.performTasks(Target.java:413)
    at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.Main.runBuild(Main.java:811)
    at org.apache.tools.ant.Main.startAnt(Main.java:217)
    at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
    at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)