title: Pycharm converts whitespace and won't convert back
body: <p>I am having an issue with Pycharm where certain files tracked by git will show up as having been modified when I haven't done anything but visit the file. Usually the modifications are tabs being changed to spaces or vice-versa, or tabs being added to/removed from empty lines. Once this kind of modification is made, I can't seem to roll back the changes no matter what I do. I have "keep indents on empty lines" set everywhere it can be set in settings, but Pycharm will still remove indents on some empty lines, and even when I re-add them or revert local changes to the document, as soon as I navigate away from the file it will show as modified again, and the tabs have once again been removed...I assume this is something that I am doing unknowingly, or a setting that I have set rather than a bug in Pycharm, but it is driving me crazy! Any ideas how to solve this issue?</p>