title: unable to commit a file, accidentally renamed with mv
body: <p>I've accidentally used mv to rename a file which was under git. I renamed the 
  file from lower case to uppercase keeping the name same.</p>
  
  <p>mv abc.java ABC.java</p>
  
  <p>I've also made changes and committed the file after that . </p>
  
  <p>How do I now make an actual git rename of this file? Git bash doesn't seem to understand the difference between ABC.java and abc.java.</p>
  
  <p>I'm not sure what changed on master(by others) but after moving to a branch, I'm no more able to commit my changes to the file. It says the old file index still exists.</p>
  
  <p><strong>$ git commit -m "renamed to uppercase" ABC.java 
  fatal: Will not add file alias 
  'dir1/ABC.java' ('dir1/abc.java' already exists in index)</strong></p>
  
  <p>When I do git status, it shows the renamed files but doesn't let me commit the renamed files.  If I try to do a delete abc.java(which is actually not present at least locally), again (I think because of case insensitivity) git deletes the new one.</p>
  
  <p>If I clone a new repo out of this, the repo still pulls out the files with old name(abc.java) but all my changes until the recently failing ones are there in it.</p>