[PATCH] git p4: Use git diff-tree instead of format-patch

The output of git format-patch can vary with user preferences. In
particular setting diff.noprefix will break the "git apply" that
is done as part of "git p4 submit".

Signed-off-by: Crestez Dan Leonard <redacted>
---
  git-p4.py | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)