ignore blank line removals

If the contents of a file initially are:
  one

  three
and on branch A there is a commit, removing the blank line:
  one
  three
and on branch B there is a commit, adding 'two':
  one
  two
  three
Normally, if you try to merge A into B (or B into A), git recognizes a
decision needs to be made between removing the second line or add
"two" to the second line. It would be convenient to have a merge
strategy that defaults to the latter in cases where the removed line
was a blank line (or a line containing only whitespace) ...something
like -Xignore-blank-line-removals.