title: How do I resolve a conflict after git pull?
body: <p>I have to solve some conflict after a <code>git pull</code>.</p>
  
  <pre><code>$ git pull
  CONFLICT (rename/add): Renamed vignette_generator_mashed.h-&gt;vision_problem_8.h in 49423dd0d47abe6d839a783b5517bdfd200a202f. vision_problem_8.h added in HEAD
  Added as vision_problem_8.h~HEAD_1 instead
  Removed vignette_generator_cross_square.cc
  Automatic merge failed; fix conflicts and then commit the result.
  </code></pre>
  
  <p>So I googled it a bit, and found people saying using <code>git mergetool</code>. But here is what I got:</p>
  
  <pre><code>$ git mergetool
  merge tool candidates: meld kdiff3 tkdiff xxdiff meld gvimdiff emerge opendiff emerge vimdiff
  No files need merging
  $ git mergetool opendiff
  merge tool candidates: meld kdiff3 tkdiff xxdiff meld gvimdiff emerge opendiff emerge vimdiff
  opendiff: file not found
  </code></pre>
  
  <p>So does it mean I have to install something?</p>
  
  <p>What if I simply want the version from <code>git pull</code> to overwrite everything?</p>