also remove empty lines from output of LEAF_PACKAGES command

Author: lexming

ncm-spma/src/main/perl/spma/yum.pm

@@ -694,7 +694,7 @@ sub packages_to_remove
 
     # The leaf set doesn't contain the header lines, which are just
     # garbage.
-    my $leaves = Set::Scalar->new(grep($_ !~ m{\s}, split(/\n/, $out)));
+    my $leaves = Set::Scalar->new(grep($_ !~ m{^$|\s}, split(/\n/, $out)));
 
     my $candidates = $leaves-$wanted;