No lazy loading if $load_exons is true.

If $load_exons is true, do not do lazy loading in any case (including when the number of transcripts is 1).

modules/Bio/EnsEMBL/DBSQL/TranscriptAdaptor.pm

@@ -493,8 +493,8 @@ sub fetch_all_by_Slice {
 
   my $transcripts = $self->SUPER::fetch_all_by_Slice_constraint( $slice, $constraint, $logic_name);
 
-  # if there are 0 or 1 transcripts still do lazy-loading
-  if ( !$load_exons || @$transcripts < 2 ) {
+  # if there are 0 transcripts still do lazy-loading
+  if ( !$load_exons || @$transcripts < 1 ) {
     return $transcripts;
   }