we had consistently used tabs instead of spaces for indentation. It seems, that everyone using spaces wants them to act as tabs anyways and sets up the IDE to treat them as such. (eg. you never want to indent 3 instead of 4 spaces, so pressing backspace once you expect to remove all 4 spaces)
It seems this was (deliberately...) destroyed by commits like 1ce2f25a . I vote towards reverting this (and similar) commits.
If there is a good argument for spaces over tabs we can also have a vote over what should be used or similar, but i think we should have a uniform style in the code.