message: tools: including working tree in modified_since_last_github_commit.sh diff.
  This avoids proto_format.sh getting confused by uncommitted changes.
  Risk level: Low (tooling only)
  Testing: Manual
diff: @@ -4,4 +4,4 @@ declare -r BASE="$(dirname "$0")"
  declare -r TARGET_PATH=$1
  declare -r EXTENSION=$2
  -git diff --name-only $("${BASE}"/last_github_commit.sh)..HEAD | grep "\.${EXTENSION}$"
  +git diff --name-only $("${BASE}"/last_github_commit.sh) | grep "\.${EXTENSION}$"
  