Fix previous release detection

The previous release detection mechanism was broken. Also since we do
not handle correctly when BB should do install and upgrade tests, let's
skip (by not failing) test that can't succeed since packages where not
released.

scripts/bash_lib.sh

@@ -180,17 +180,21 @@ deb_setup_mariadb_mirror() {
     bb_log_err "missing the branch variable"
     exit 1
   }
-  branch=$1
-  if [[ $branch == "$development_branch" ]]; then
-    #TOFIX - temp hack
-    prev_released=$((${branch/1[0-9]./} - 1))
-    if ((prev_released < 0)); then
-      branch="10.11"
+  branch_tmp=$1
+  major=${branch_tmp%.*}
+  minor=${branch_tmp##*.}
+  if ((minor == 0)); then
+    if ((major == 11)); then
+      prev_release="10.11"
     else
-      branch="10.$prev_released"
+      bb_log_err "Unknown previous branch for $branch_tmp, please update this script"
+      exit 1
     fi
-    bb_log_info "using previous $branch released version for development branch $1"
+  else
+    prev_release="$major.$((minor - 1))"
   fi
+  branch=$prev_release
+  bb_log_info "using previous $branch released version for development branch $1"
   bb_log_info "setup MariaDB repository for $branch branch"
   command -v wget >/dev/null || {
     bb_log_err "wget command not found"
@@ -209,8 +213,12 @@ deb_setup_mariadb_mirror() {
       exit 1
     }
   else
-    bb_log_err "deb_setup_mariadb_mirror: $branch packages for $dist_name $version_name does not exist on https://deb.mariadb.org/"
-    exit 1
+    # the correct way of handling this would be to not even start the check
+    # since we know it will always fail. But apparently, it's not going to
+    # happen soon in BB. Once done though, replace the warning with an error
+    # and use a non-zero exit code.
+    bb_log_warn "deb_setup_mariadb_mirror: $branch packages for $dist_name $version_name does not exist on https://deb.mariadb.org/"
+    exit 0
   fi
   set +u
 }
@@ -246,14 +254,18 @@ upgrade_test_type() {
       prev_major_version=$major_version
       ;;
     "major")
-      #TOFIX - temp hack
-      minor_version=${major_version/1[0-9]./}
-      if ((minor_version == 0)); then
-        prev_minor_version=11
+      major=${major_version%.*}
+      minor=${major_version##*.}
+      if ((minor == 0)); then
+        if ((major == 11)); then
+          prev_major_version="10.11"
+        else
+          bb_log_err "Unknown previous branch for $branch_tmp, please update this script"
+          exit 1
+        fi
       else
-        prev_minor_version=$((minor_version - 1))
+        prev_major_version="$major.$((minor - 1))"
       fi
-      prev_major_version="10.$prev_minor_version"
       ;;
     *)
       bb_log_err "test type not provided"