ci: minor fixes for nightly testing

Updating rules for Installer and Regression testing and fixing failures
if certain variables are not set.

schutzbot/deploy.sh

@@ -103,7 +103,7 @@ if [ -f "rhel8internal.repo" ]; then
     sudo mv rhel8internal.repo /etc/yum.repos.d/
     # Use osbuild from schutzfile if desired for testing custom osbuild-composer packages
     # specified by $REPO_URL in ENV and used in prepare-rhel-internal.sh
-    if [ "$SCHUTZ_OSBUILD" == 1 ]; then
+    if [ "${SCHUTZ_OSBUILD:=false}" == true ]; then
         sudo rm -f /etc/yum.repos.d/osbuild-composer.repo
     else
         sudo rm -f /etc/yum.repos.d/osbuild*.repo

schutzbot/prepare-rhel-internal.sh

@@ -64,7 +64,7 @@ cp rhel-8.json rhel-8-beta.json
 
 JOB_NAME="${JOB_NAME:-${CI_JOB_ID}}"
 # Do not create tests repo if it's provided from ENV
-if [ -z "$REPO_URL" ]; then
+if [ -z "${REPO_URL+x}" ]; then
     greenprint "📦 Installing requirements"
     sudo dnf -y install createrepo_c wget python3-pip