Clear $1 prior to calling plugins

xcatd now might let $1 leak into the plugins.  Ideally, the downstream code
would check match before relying upon $1 to be undef, but better to
avoid unintuitive behavior.

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@16997 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd

xCAT-server/sbin/xcatd

@@ -1714,6 +1714,7 @@ sub dispatch_request {
     }
     if ($onlyone and not ($_->{'_xcatdest'} and xCAT::NetworkUtils->thishostisnot($_->{'_xcatdest'}))) {
         $SIG{CHLD}='DEFAULT';
+        "" =~ m/()/; #clear $1 that we may have sitting around
 	if ($_->{'_xcatdelay'} and not ref $_->{'_xcatdelay'}) { sleep $_->{'_xcatdelay'}; }
         ${"xCAT_plugin::".$modname."::"}{process_request}->($_,$dispatch_cb,\&do_request);
         return;