da312e6220
In continations (that use spaces for alignment), don't allow the number of leading tabs to change. Previously only removal of tabs was disallowed, but addition doesn't make sense either, as only spaces should be used for further alignemnt. This catches situations like this: |<-tab->all_work_and_no_play (makes, |<-tab-> jack, |<-tab-><-tab-> a dull boy);