Work around yum/dnf differences

Some minor workarounds for Fedora >= 22 where dnf is the default
package manager. The changes are documented on the Fedora release
notes https://fedoraproject.org/wiki/Changes/ReplaceYumWithDNF

Change-Id: I7d7d6f5d294980dcb217d6190a1efd9e0bbea9a6

elements/rpm-distro/pre-install.d/01-override-yum-arch

@@ -25,5 +25,11 @@ else
     exit 1
 fi
 
+if [ $DIB_RELEASE -ge 22 ]; then
+    mkdir -p /etc/dnf/vars
+    echo $basearch > /etc/dnf/vars/basearch
+    echo $arch > /etc/dnf/vars/basearch
+else
     echo $basearch > /etc/yum/vars/basearch
     echo $arch > /etc/yum/vars/arch
+fi

elements/yum/post-install.d/99-reset-yum-conf

@@ -6,5 +6,11 @@ fi
 set -eu
 set -o pipefail
 
-sed -i 's/keepcache=1/keepcache=0/' /etc/yum.conf
+if [ $DIB_RELEASE -ge 22 ]; then
-sed -i 's/cachedir=\/tmp\/yum/cachedir=\/var\/cache\/yum/' /etc/yum.conf
+    cfg=/etc/dnf/dnf.conf
+else
+    cfg=/etc/yum.conf
+fi
+
+sed -i 's/keepcache=1/keepcache=0/' $cfg
+sed -i 's/cachedir=\/tmp\/yum/cachedir=\/var\/cache\/yum/' $cfg

elements/yum/pre-install.d/01-yum-keepcache

@@ -6,5 +6,14 @@ fi
 set -eu
 set -o pipefail
 
-sed -i 's/keepcache=0/keepcache=1/' /etc/yum.conf
+if [ $DIB_RELEASE -ge 22 ]; then
-sed -i 's/cachedir=\/var\/cache\/yum/cachedir=\/tmp\/yum/' /etc/yum.conf
+    # dnf is slightly different; doesn't have these by default
+    cfg=/etc/dnf/dnf.conf
+    echo "keepcache=1" >> $cfg
+    echo "cachedir=/tmp/yum" >> $cfg
+else
+    cfg=/etc/yum.conf
+    sed -i 's/keepcache=0/keepcache=1/' $cfg
+    sed -i 's/cachedir=\/var\/cache\/yum/cachedir=\/tmp\/yum/' $cfg
+fi
+