title: Git shows merge conflicts on old resolved commit while rebasing
body: <p>I have an existing repo for which I need to change all the author emails on all the commits (I'm the only one who works on that repo).</p>
  <pre><code>git rebase --root --exec 'git commit --amend --author=&quot;Arthur ATTOUT &lt;new.email@company.com&gt;&quot; --no-edit'
  </code></pre>
  <p>While the first ~100 commits are treated properly, upon a specific commit, git freaks out and complains there is a conflict</p>
  <pre><code>error: could not apply 0709cb2... Unit32 default value watermark
  Resolve all conflicts manually, mark them as resolved with
  &quot;git add/rm &lt;conflicted_files&gt;&quot;, then run &quot;git rebase --continue&quot;.
  You can instead skip this commit: run &quot;git rebase --skip&quot;.
  To abort and get back to the state before &quot;git rebase&quot;, run &quot;git rebase --abort&quot;.
  Could not apply 0709cb2... Unit32 default value watermark
  Auto-merging ViewModels/ViewModels/DataprepControl.cs
  CONFLICT (content): Merge conflict in ViewModels/ViewModels/DataprepControl.cs
  me@home MINGW64 ~/source/repos/soft (dev|REBASE-i 129/320)
  </code></pre>
  <p>Why does git suddenly realises there is a conflict in those super old commits ? Shouldn't rebase take into account conflicts resolution I have applied at that time ?</p>