prioritize installation

common/Dockerfile.header

@@ -11,10 +11,8 @@ FROM _BASE_IMAGE_
 # do not run for slc6 because of BMK-671
 RUN yum repolist
 RUN if [ `grep -c "Scientific Linux CERN" /etc/redhat-release` -ne 1 ]; then \
-        yum install -y  centos-release epel-release \   
-                        unzip bzip2 \
-                        which man file util-linux gcc \
-                        wget tar freetype perl jq && \
+        yum install -y  centos-release epel-release ; \
+        yum install -y  unzip bzip2 which man file util-linux gcc wget tar freetype perl jq && \
         yum clean all; \
     fi