title: Eclipse Egit : Label decorations does not show and option does not remain checked
body: <p>Without any apparent reason (no update whatsoever), since a few days the EGit text decoration doesn't show up in Eclipse any more.
  It is unchecked in "Window > Preferences > General > Appearance > Label Decorations > Git", and I cannot check it!! If I check it and "Apply" and "OK", nothing happens and it remains unchecked...</p>
  
  <p>My Eclipse log goes like :</p>
  
  <pre><code>!ENTRY org.eclipse.ui.workbench 4 2 2013-04-05 14:18:08.926
  !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.ui.workbench".
  !STACK 0
  org.eclipse.jgit.errors.RevWalkException: Walk failure.
      at org.eclipse.jgit.revwalk.RevWalk.iterator(RevWalk.java:1237)
      at org.eclipse.jgit.revwalk.RevWalkUtils.find(RevWalkUtils.java:129)
      at org.eclipse.jgit.revwalk.RevWalkUtils.count(RevWalkUtils.java:94)
      at org.eclipse.jgit.lib.BranchTrackingStatus.of(BranchTrackingStatus.java:100)
      at org.eclipse.egit.ui.internal.decorators.DecoratableResourceHelper.getBranchStatus(DecoratableResourceHelper.java:48)
      at org.eclipse.egit.ui.internal.decorators.DecoratableResourceAdapter.&lt;init&gt;(DecoratableResourceAdapter.java:72)
      at org.eclipse.egit.ui.internal.decorators.GitLightweightDecorator.decorateResource(GitLightweightDecorator.java:189)
      at org.eclipse.egit.ui.internal.decorators.GitLightweightDecorator.decorate(GitLightweightDecorator.java:166)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorDefinition.decorate(LightweightDecoratorDefinition.java:263)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorManager$LightweightRunnable.run(LightweightDecoratorManager.java:81)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorManager.decorate(LightweightDecoratorManager.java:365)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorManager.getDecorations(LightweightDecoratorManager.java:347)
      at org.eclipse.ui.internal.decorators.DecorationScheduler$1.ensureResultCached(DecorationScheduler.java:371)
      at org.eclipse.ui.internal.decorators.DecorationScheduler$1.run(DecorationScheduler.java:331)
      at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
  Caused by: org.eclipse.jgit.errors.MissingObjectException: Missing commit 11d64b0d91bf24bfb551fbf20c3f6b244dacd74a
      at org.eclipse.jgit.storage.file.WindowCursor.open(WindowCursor.java:127)
      at org.eclipse.jgit.revwalk.RevWalk.getCachedBytes(RevWalk.java:861)
      at org.eclipse.jgit.revwalk.RevCommit.parseHeaders(RevCommit.java:142)
      at org.eclipse.jgit.revwalk.PendingGenerator.next(PendingGenerator.java:148)
      at org.eclipse.jgit.revwalk.DelayRevQueue.next(DelayRevQueue.java:86)
      at org.eclipse.jgit.revwalk.FixUninterestingGenerator.next(FixUninterestingGenerator.java:77)
      at org.eclipse.jgit.revwalk.StartGenerator.next(StartGenerator.java:181)
      at org.eclipse.jgit.revwalk.RevWalk.next(RevWalk.java:422)
      at org.eclipse.jgit.revwalk.RevWalk.iterator(RevWalk.java:1235)
      ... 15 more
  
  !ENTRY org.eclipse.ui 4 4 2013-04-05 14:18:08.927
  !MESSAGE Exception in Decorator. The 'Git' decorator will be disabled.
  
  !ENTRY org.eclipse.ui 4 4 2013-04-05 14:18:08.927
  !MESSAGE Walk failure.
  !STACK 0
  org.eclipse.jgit.errors.MissingObjectException: Missing commit 11d64b0d91bf24bfb551fbf20c3f6b244dacd74a
      at org.eclipse.jgit.storage.file.WindowCursor.open(WindowCursor.java:127)
      at org.eclipse.jgit.revwalk.RevWalk.getCachedBytes(RevWalk.java:861)
      at org.eclipse.jgit.revwalk.RevCommit.parseHeaders(RevCommit.java:142)
      at org.eclipse.jgit.revwalk.PendingGenerator.next(PendingGenerator.java:148)
      at org.eclipse.jgit.revwalk.DelayRevQueue.next(DelayRevQueue.java:86)
      at org.eclipse.jgit.revwalk.FixUninterestingGenerator.next(FixUninterestingGenerator.java:77)
      at org.eclipse.jgit.revwalk.StartGenerator.next(StartGenerator.java:181)
      at org.eclipse.jgit.revwalk.RevWalk.next(RevWalk.java:422)
      at org.eclipse.jgit.revwalk.RevWalk.iterator(RevWalk.java:1235)
      at org.eclipse.jgit.revwalk.RevWalkUtils.find(RevWalkUtils.java:129)
      at org.eclipse.jgit.revwalk.RevWalkUtils.count(RevWalkUtils.java:94)
      at org.eclipse.jgit.lib.BranchTrackingStatus.of(BranchTrackingStatus.java:100)
      at org.eclipse.egit.ui.internal.decorators.DecoratableResourceHelper.getBranchStatus(DecoratableResourceHelper.java:48)
      at org.eclipse.egit.ui.internal.decorators.DecoratableResourceAdapter.&lt;init&gt;(DecoratableResourceAdapter.java:72)
      at org.eclipse.egit.ui.internal.decorators.GitLightweightDecorator.decorateResource(GitLightweightDecorator.java:189)
      at org.eclipse.egit.ui.internal.decorators.GitLightweightDecorator.decorate(GitLightweightDecorator.java:166)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorDefinition.decorate(LightweightDecoratorDefinition.java:263)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorManager$LightweightRunnable.run(LightweightDecoratorManager.java:81)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorManager.decorate(LightweightDecoratorManager.java:365)
      at org.eclipse.ui.internal.decorators.LightweightDecoratorManager.getDecorations(LightweightDecoratorManager.java:347)
      at org.eclipse.ui.internal.decorators.DecorationScheduler$1.ensureResultCached(DecorationScheduler.java:371)
      at org.eclipse.ui.internal.decorators.DecorationScheduler$1.run(DecorationScheduler.java:331)
      at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
  </code></pre>
  
  <p>My conf :</p>
  
  <pre><code>Eclipse Platform
  Version: 4.2.2
  Build id: M20130204-1200
  
  Eclipse Dynamic Languages Toolkit - Index Frameworks
  Version: 4.0.0.201206120848
  
  Eclipse EGit
  Version: 2.2.0.201212191850-r
  </code></pre>
  
  <p>Thanks for your help!</p>