detect-environment: changed two if's to if/elif

If the former if condition is true, then the latter implicitly cannot be
true. Hence, there is no point in evaluating it.

Ticket: ENT-12600
Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>

Author: larsewi

build-scripts/detect-environment

@@ -213,8 +213,8 @@ detect_distribution()
     if [ "$os" = "sles" ]; then
       OS=sles
       OS_VERSION="$ver"
-    fi
-    if expr "$os" : "opensuse" >/dev/null; then
+    elif expr "$os" : "opensuse" >/dev/null; then
+      # If the string begins with "opensuse", then strip the remaining part. It
       # can be "opensuse-leap" or "opensuse-tumbleweed"
       OS=opensuse
       OS_VERSION="$ver"