Change how we gate requirements installs

dev-requirements may conflict with the other two files... so install
them first, then install dev-requirements.txt

Change-Id: I16698b35b90639297a75c1fed84acf6e3497ec66

modules/openstack_project/files/jenkins_job_builder/config/requirements.yaml

@@ -9,7 +9,7 @@
           /usr/local/jenkins/slave_scripts/select-mirror.sh openstack requirements
           virtualenv --clear .venv
           PIP_ARGS=""
-          REQ_FILES="tools/pip-requires tools/test-requires requirements.txt test-requirements.txt dev-requirements.txt"
+          REQ_FILES="tools/pip-requires tools/test-requires requirements.txt test-requirements.txt"
           for FILE in $REQ_FILES
           do
             if [ -e $FILE ]
@@ -21,6 +21,9 @@
           done
           # Run the same basic pip command that the mirror script runs.
           .venv/bin/pip install -M -U --exists-action=w $PIP_ARGS
+          if [ -e dev-requirements.txt ] ; then
+              .venv/bin/pip install -M -U --exists-action=w dev-requirements.txt
+          fi
 
     publishers:
       - console-log