You should never have to redownload unless somebody is carelessly force oushing changes to the remote. If you're about to do something 'weird' like fix a merge

You should never have to redownload unless somebody is carelessly force oushing changes to the remote. If you're about to do something 'weird' like fix a merge conflict, you can save the changes by creating a branch. Sometimes you have to go back and fix a previous commit to reconcile a conflict. The 'gitk --all' command is your friend here. With it it's easy to visualize the history, reset, cherry-pick commits, etc.