Fix CI build error (#37424)

Fix CI build error

paddle/scripts/paddle_build.sh

@@ -2459,7 +2459,7 @@ function build_pr_and_develop() {
     mkdir ${PADDLE_ROOT}/build/pr_whl && cp ${PADDLE_ROOT}/build/python/dist/*.whl ${PADDLE_ROOT}/build/pr_whl
     rm -f ${PADDLE_ROOT}/build/python/dist/*.whl && rm -f ${PADDLE_ROOT}/build/python/build/.timestamp
     cmake_change=`git diff --name-only upstream/$BRANCH | grep "cmake/external" || true`
-    if [ ${cmake_change} ];then
+    if [[ ${cmake_change} ]];then
         rm -rf ${PADDLE_ROOT}/build/Makefile ${PADDLE_ROOT}/build/CMakeCache.txt
         rm -rf ${PADDLE_ROOT}/build/third_party
     fi