fix(ci/dockerfile.apisix-test-busted): build image fail (#76)

src/apisix/ci/Dockerfile.apisix-test-busted

@@ -3,14 +3,16 @@ FROM apache/apisix:$APISIX_VERSION-centos
 
 # in github action, change the source of yum is not ok
 # note: uncomment below if it's slow to build image
-# RUN mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup && \ 
+# RUN mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup && \
 #     curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.cloud.tencent.com/repo/centos7_base.repo && \
 #     yum clean all
 
 RUN yum install -y sudo make gcc curl wget unzip git valgrind
 
 ARG APISIX_VERSION
 RUN curl https://raw.githubusercontent.com/apache/apisix/${APISIX_VERSION}/utils/linux-install-luarocks.sh | bash
+# lock the version of luasystem, otherwise the busted won't be installed success
+RUN luarocks install https://luarocks.org/manifests/lunarmodules/luasystem-0.2.1-0.rockspec
 RUN luarocks install https://github.com/lunarmodules/busted/releases/download/v2.1.1/busted-2.1.1-1.rockspec
 
 COPY ci/requirements-dev-0.rockspec /