fix(xcatd): stop a noderange from running a command through the ^ operator

The ^ noderange operator reads node names from a file. NodeRange opened
that file with a two-argument open. A two-argument open reads shell
metacharacters in the path, so a noderange such as ^"id|" ran a command.
xcatd expands a noderange while it processes a request, so the command
ran on the management node.

Use a three-argument open with an explicit read mode. The value is then
only ever a file name. The ^ operator keeps working: ^/tmp/nodes still
reads the file.

This fix was recovered from the lenovobuild branch. The original there
(commit for "Remove load from file in noderange support") removed the ^
operator. This keeps the documented operator and closes the command path
instead.

perl-xCAT/xCAT/NodeRange.pm

@@ -678,8 +678,9 @@ sub noderange {
         if ($atom eq '') { next; }
 
         if ($atom =~ /^\^(.*)$/) {    # get a list of nodes from a file
-            open(NRF, $1);
-            while (<NRF>) {
+            my $nrfile = $1;
+            open(my $nrf, '<', $nrfile) or next;
+            while (<$nrf>) {
                 my $line = $_;
                 unless ($line =~ m/^[\^#]/) {
                     $line =~ m/^([^:	 ]*)/;
@@ -692,7 +693,7 @@ sub noderange {
                     }
                 }
             }
-            close(NRF);
+            close($nrf);
             next;
         }