make PADDLE_ENFORCE ci check rule more robust (#19445)

tools/check_api_approvals.sh

@@ -116,7 +116,7 @@ if [ ${HAS_DEFINE_FLAG} ] && [ "${GIT_PR_ID}" != "" ]; then
     fi
 fi
 
-HAS_PADDLE_ENFORCE_FLAG=`git diff -U0 upstream/$BRANCH |grep -v "PADDLE_ENFORCE_" |grep -o -m 1 "PADDLE_ENFORCE" || true`
+HAS_PADDLE_ENFORCE_FLAG=`git diff -U0 upstream/$BRANCH |grep "+" |grep -v "PADDLE_ENFORCE_" |grep -o -m 1 "PADDLE_ENFORCE" || true`
 if [ ${HAS_PADDLE_ENFORCE_FLAG} ] && [ "${GIT_PR_ID}" != "" ]; then
     APPROVALS=`curl -H "Authorization: token ${GITHUB_API_TOKEN}" https://api.github.com/repos/PaddlePaddle/Paddle/pulls/${GIT_PR_ID}/reviews?per_page=10000 | \
     python ${PADDLE_ROOT}/tools/check_pr_approval.py 1 6836917 47554610 22561442`