title: Conflict when squashing linear commit history
body: <p>How is it possible that when trying to squash/fixup a <strong>linear</strong> branch I still have to do manual merges? The repo has been converted from Subversion. Every conflict is either "Automatic cherry-pick failed" or "Aborting commit due to empty commit message". The latter I could understand, but a <code>--fixup-empty</code> or something would be useful.</p>
  
  <p>Typical output:</p>
  
  <pre><code>user@machine:/path (master|REBASE-i)$ git add * &amp;&amp; git rebase --continue 
  [detached HEAD c536940] fixup!
   Author: John Doe &lt;John.doe@example.com&gt;
   2 files changed, 57 insertions(+), 4 deletions(-)
  Automatic cherry-pick failed.  After resolving the conflicts,
  mark the corrected paths with 'git add &lt;paths&gt;', and
  run 'git rebase --continue'
  Could not apply 8854a54... &gt;6d5f180 foo
  user@machine:/path (master|REBASE-i)$ git st
  # Not currently on any branch.
  # Unmerged paths:
  #   (use "git reset HEAD &lt;file&gt;..." to unstage)
  #   (use "git add/rm &lt;file&gt;..." as appropriate to mark resolution)
  #
  #   both modified:      filename.ics
  #
  no changes added to commit (use "git add" and/or "git commit -a")
  </code></pre>