CI Testing: Ensure smooth installation od the build under test

Make sure the build under test installs smoothly including the
multilib subpackages needed for the CI tests.  Use a setup task
prepare.sh to accomplish that.

The "standard" CI installer installs whole the x86_64 build
minus glibc-headers-s390, which is a noarch package having
file conflicts with glibc-headers-x86 (which is another
noarch subrpm).  The prepare.sh then installs needed i686
packages.

plans/ci.fmf

@@ -1,10 +1,13 @@
 summary: CI Gating Plan
 discover:
     how: fmf
-    directory: tests
 prepare:
-    how: install
-    exclude:
-      - glibc-headers-s390
+    - name: prepare
+      how: shell
+      script: ./plans/prepare.sh
+    - name: install
+      how: install
+      exclude:
+          - glibc-headers-s390
 execute:
     how: tmt

plans/prepare.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+#
+# Setup task for x86_64 Fedora CI systems. 
+# KOJI_TASK_ID per https://github.com/fedora-ci/dist-git-pipeline/pull/50 .
+#
+
+set -x
+
+true "V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V-V"
+
+echo "KOJI_TASK_ID=$KOJI_TASK_ID"
+
+. /etc/os-release
+
+if [ "$ID" == "fedora" ] && [ "$(arch)" == "x86_64" ]; then
+
+    if [ -z "${KOJI_TASK_ID}" ]; then
+        echo "Missing koji task ID, skipping ..."
+        exit 0
+    fi
+
+    tmpd=`mktemp -d`
+    pushd $tmpd
+        koji download-task $KOJI_TASK_ID --noprogress --arch=src
+        ls
+        VR=$(rpm -qp glibc* --queryformat='%{version}-%{release}')
+    popd
+    rm -rf $tmpd
+
+    tmpd=`mktemp -d`
+    pushd $tmpd
+        koji download-task $KOJI_TASK_ID --noprogress --arch=x86_64 --arch=noarch
+        rm -f *debuginfo* glibc-headers-s390*
+        ls
+        dnf -y install *.rpm
+    popd
+    rm -rf $tmpd
+
+    tmpd=`mktemp -d`
+    pushd $tmpd
+        koji download-task $KOJI_TASK_ID --noprogress --arch=i686
+        rm -f *debuginfo*
+        ls
+        yum -y install glibc-$VR* glibc-devel-$VR*
+    popd
+    rm -rf $tmpd
+else
+    echo "Not Fedora x86_64, skipping..."
+fi
+
+true "^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^"