Only run xen-toolstack helper script if both, xm and xl are present

Avoids warning about deprecated helper script.

NEWS.markdown

@@ -38,6 +38,8 @@ Other Changes
   `deb.debian.org` except those for the `debian-archive`. The latter
   now point to `archive.debian.org` directly.
 * Many improvements for the release-testing script.
+* Only run xen-toolstack helper script if both, xm and xl are
+  present. Avoids warning about deprecated helper script.
 
 
 xen-tools 4.7 (released 23 Jan 2017)

debian/changelog

@@ -22,6 +22,8 @@ xen-tools (4.8-1) UNRELEASED; urgency=medium
     + Drop pygrub path detection from xm.tmpl, Xen prefers a path-less
       bootloader='pygrub'.
     + Many improvements for the release-testing script.
+    + Only run xen-toolstack helper script if both, xm and xl are
+      present. Avoids warning about deprecated helper script.
 
     [ Nico Boehr ]
     + Add support for LVM thin provisioning.

lib/Xen/Tools/Common.pm

@@ -161,18 +161,19 @@ sub findXenToolstack
 {
     my $helper = '/usr/lib/xen-common/bin/xen-toolstack';
 
-    if (-x $helper) {
+    my $xm = which('xm');
+    my $xl = which('xl');
+
+    if ($xm and $xl and -x $helper) {
         my $toolstack = `$helper`;
         chomp($toolstack);
         return $toolstack if $toolstack;
     }
 
-    my $xm = which('xm');
     if ($xm and system("$xm list >/dev/null 2>/dev/null") == 0) {
         return $xm;
     }
 
-    my $xl = which('xl');
     if ($xl and system("$xl list >/dev/null 2>/dev/null") == 0) {
         return $xl;
     }