title: Git add not working with .png files?
body: <p>I have a dirty working tree, dirty because I made changes to source files and touched up some images. I was trying to add just the images to the index, so I ran this command:</p>
  
  <pre><code>git add *.png
  </code></pre>
  
  <p>But, this doesn't add the files. There were a few <i>new</i> image files that were added, but none of the ones that were modified/pre-existing were added.</p>
  
  <p>What gives?</p>
  
  <p><b>Edit</b>: Here is some relevant terminal output</p>
  
  <pre><code>$ git status
  # On branch master
  #
  # Changed but not updated:
  #   (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:   src/main/java/net/plugins/analysis/FormMatcher.java
  #   modified:   src/main/resources/icons/doctor_edit_male.png
  #   modified:   src/main/resources/icons/doctor_female.png
  #
  # Untracked files:
  #   (use "git add &lt;file&gt;..." to include in what will be committed)
  #
  #   src/main/resources/icons/arrow_up.png
  #   src/main/resources/icons/bullet_arrow_down.png
  #   src/main/resources/icons/bullet_arrow_up.png
  no changes added to commit (use "git add" and/or "git commit -a")
  </code></pre>
  
  <p>Then executed "git add *.png" (no output after command)</p>
  
  <p>Then:</p>
  
  <pre><code>$ git status
  # On branch master
  #
  # Changes to be committed:
  #   (use "git reset HEAD &lt;file&gt;..." to unstage)
  #
  #   new file:   src/main/resources/icons/arrow_up.png
  #   new file:   src/main/resources/icons/bullet_arrow_down.png
  #   new file:   src/main/resources/icons/bullet_arrow_up.png
  #
  # Changed but not updated:
  #   (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:   src/main/java/net/plugins/analysis/FormMatcher.java
  #   modified:   src/main/resources/icons/doctor_edit_female.png
  #   modified:   src/main/resources/icons/doctor_edit_male.png
  </code></pre>