git-cvsimport-script: update cvsps cache instead of rebuilding it

Updating the cache is sufficient for most purposes.
If users really want to rebuild the cache, they can specify
the option themselves.

git-cvsimport-script

@@ -436,7 +436,7 @@ die "Cannot fork: $!\n" unless defined $pid;
 unless($pid) {
 	my @opt;
 	@opt = split(/,/,$opt_p) if defined $opt_p;
-	exec("cvsps",@opt,"-x","-A","--cvs-direct",'--root',$opt_d,$cvs_tree);
+	exec("cvsps",@opt,"-u","-A","--cvs-direct",'--root',$opt_d,$cvs_tree);
 	die "Could not start cvsps: $!\n";
 }