Drop pygrub path detection from xm.tmpl

Xen prefers a path-less bootloader='pygrub'.

NEWS.markdown

@@ -16,6 +16,8 @@ Bug Fixes
 * Minor documentation fixes.
 * Eliminate progress reporting which is useless in logs. (Yuri Sakhno,
   GH #42)
+* Drop pygrub path detection from xm.tmpl, Xen prefers a path-less
+  bootloader='pygrub'.
 
 Distribution Releases Changes
 -----------------------------

debian/changelog

@@ -19,6 +19,8 @@ xen-tools (4.8-1) UNRELEASED; urgency=medium
       except those for the debian-archive. The latter now point to
       archive.debian.org directly.
     + Set Ubuntu fallback suite to the latest LTS, i.e. 18.04 Bionic.
+    + Drop pygrub path detection from xm.tmpl, Xen prefers a path-less
+      bootloader='pygrub'.
 
     [ Nico Boehr ]
     + Add support for LVM thin provisioning.

etc/xm.tmpl

@@ -20,20 +20,7 @@
 {
   if ( $pygrub )
   {
-    my $pygrub_bin = '';
-    foreach my $pygrub_path (reverse glob('/usr/lib/xen-default/bin/pygrub
-                                           /usr/lib/xen-*/bin/pygrub
-                                           /usr/*bin/pygrub
-                                           /usr/local/bin/pygrub')) {
-      if (-x $pygrub_path) {
-        $pygrub_bin = $pygrub_path;
-        last;
-      }
-    }
-
-    die "pygrub not found" unless $pygrub_bin;
-
-    $OUT .= "bootloader = '$pygrub_bin'\n";
+    $OUT .= "bootloader = 'pygrub'\n";
   }
 }
 vcpus       = '{$vcpus}'