title: Git conflict during squashing in interactive rebase
body: <p>I've the following git history</p>
  
  <pre><code>* bee55e9 (HEAD -&gt; WM-290) - Jepessen : Little refactoring. (4 minutes ago)
  * 1a4470a - Jepessen : Project refactoring (5 minutes ago)
  * 399f769 - Jepessen : Added some documentation. (15 minutes ago)
  * cb1055e - Jepessen : Another Test passed. (21 minutes ago)
  * 549f147 - Jepessen : Another test passed. (24 minutes ago)
  * b77c862 - Jepessen : First test passed. (29 minutes ago)
  * d2c9d86 - Jepessen : Integer -&gt; IntegerValue: Failing test added. (31 minutes ago)
  * 678c0b1 - Jepessen : ExpressionTest added. (2 hours ago)
  * b65284b - Jepessen : Refactored. (2 hours ago)
  * 29ccc99 - Jepessen : Solution Refactored. (2 hours ago)
  * 83f7a45 - Jepessen : Some Refactoring (2 hours ago)
  * c33b81f - Jepessen : Integer class added. (2 hours ago)
  * 1415bb4 - Jepessen : Leaf class added. (2 hours ago)
  * a25da8b - Jepessen : Added Expression project (2 hours ago)
  * aa9c4e8 (origin/master, origin/HEAD, master) - Jepessen : WMathTest C# solution added. (2 hours ago)
  * b31dc4d - Jepessen : .gitignore updated. (2 hours ago)
  * f7285b1 - Jepessen : Removed old files. (2 hours ago)
  * 8d1213c - Jepessen : .gitignore updated. (23 hours ago)
  * ed5a67a - Jepessen : WSchool project added. (24 hours ago)
  </code></pre>
  
  <p>I want to squash the <code>WM-290</code> branch into a single commit. I use the command</p>
  
  <pre><code>git rebase -i master
  </code></pre>
  
  <p>And in the interactive rebasing I write:</p>
  
  <pre><code>pick a25da8b Added Expression project
  s 1415bb4 Leaf class added.
  s c33b81f Integer class added.
  s 83f7a45 Some Refactoring
  s 29ccc99 Solution Refactored.
  s b65284b Refactored.
  s 678c0b1 ExpressionTest added.
  s d2c9d86 Integer -&gt; IntegerValue: Failing test added.
  s b77c862 First test passed.
  s 549f147 Another test passed.
  s cb1055e Another Test passed.
  s 399f769 Added some documentation.
  s 1a4470a Project refactoring
  s bee55e9 Little refactoring.
  </code></pre>
  
  <p>During rebasing I obtain the following error message:</p>
  
  <pre><code>error: Your local changes to the following files would be overwritten by merge:
          WMathTest/Expression/Expression.csproj
  Please commit your changes or stash them before you merge.
  Aborting
  Could not apply 83f7a45... Some Refactoring
  </code></pre>
  
  <p>But if I use the command <code>git mergetool</code> I obtain the following message:</p>
  
  <pre><code>$ git mergetool
  No files need merging
  </code></pre>
  
  <p>The only thing that I can do is to abort the rebasing.</p>
  
  <p>Why there's a conflict, considering that the branch is on the top of the <code>master</code> branch, and how can I solve it if no files need merging?</p>
  
  <p>EDIT:</p>
  
  <p>During the conflict, this is the output of the command <code>git status</code>:</p>
  
  <pre><code>$ git status
  interactive rebase in progress; onto aa9c4e8
  Last commands done (5 commands done):
     s 83f7a45 Some Refactoring
     s c33b81f Integer class added.
    (see more in file .git/rebase-merge/done)
  Next commands to do (11 remaining commands):
     s 83f7a45 Some Refactoring
     s 29ccc99 Solution Refactored.
    (use "git rebase --edit-todo" to view and edit)
  You are currently rebasing branch 'test' on 'aa9c4e8'.
    (all conflicts fixed: run "git rebase --continue")
  
  Changes not staged for commit:
    (use "git add &lt;file&gt;..." to update what will be committed)
    (use "git checkout -- &lt;file&gt;..." to discard changes in working directory)
  
          modified:   WMathTest/Expression/Expression.csproj
  
  no changes added to commit (use "git add" and/or "git commit -a")
  </code></pre>