I understand that it would be bad to introduce whitespace-only changes, but why would whitespace at the end of the line that doesn't break the 80 character limit be a problem otherwise? Sure, git colors them red in its diffs, but that is kind of a circular reasoning.

E.g. in this diff

  0a1
  > k=2 
  2c3,4
  <     print(i)
  ---
  >     k*=k 
  >     print(k)

you don't even see the spaces after "k=2" and "k*=k".