title: RefNotFoundException when creating a branch in JGIT
body: <p>I have a problem where i cannot create local branch.</p>
  
  <pre><code>Error: org.eclipse.jgit.api.errors.RefNotFoundException: Ref origin/sideMerge cannot be resolved
  </code></pre>
  
  <p>I have checked the following <a href="https://stackoverflow.com/questions/37130665/what-is-the-meaning-of-setstartpoint-in-jgit-when-you-move-branch">topics</a> and some others in Stackoverflow but it seems something fishy going on or something i don't understand yet.</p>
  
  <p>Can someone point me to a direction what i don't understand regarding the Ref ? 
  As far as i know the local refs starts from origin/"other_branch"</p>
  
  <p>Code snippet:</p>
  
  <pre><code>Git git;
      CreateBranchCommand tmpCreateBranch;
      git = new Git(existingRepo);
      tmpCreateBranch = git.branchCreate();
  
      try {
          tmpCreateBranch.setName(tmpBranchName).setStartPoint("origin/" + tmpBranchName).setForce(true).call();
      } catch (Exception e) {
          System.out.println("Error in Branch creation");
          System.out.println(e);
      }
  </code></pre>