title: Git Filter-Branch All command
body: <p>At the moment, I'm currently using the command, "git filter-branch --subdirectory-filter MY_DIRECTORY -- --all" to grab a certain directory from all the 30 branches in this git repo. Before I do this filter branch command I make sure to checkout every branch to make sure the --all commands works properly. </p>
  
  <p>My question is, do I have to checkout every branch before I do a git-filter all or will git-filter all still work without having to checkout all the 30 branches I'm looking at? Right now each branch is almost 3GB so this entire checkout process is taking a very long time. Any clarification would be great!</p>