[ENSCORESW-1664] Close up leaked internal cache in Gene object

modules/Bio/EnsEMBL/Gene.pm

@@ -1013,7 +1013,8 @@ sub get_all_Transcripts {
       $self->{'_transcript_array'} = $transcripts;
     }
   }
-  return $self->{'_transcript_array'};
+  my @array_copy = @{ $self->{'_transcript_array'} };
+  return \@array_copy;
 }
 
 

modules/t/gene.t

@@ -284,6 +284,13 @@ foreach my $tr (@{$gene->get_all_Transcripts()}) {
 ok($count == 5);
 ok($translates);
 
+# Verify Transcript cache is not leaky
+my $transcripts = $gene->get_all_Transcripts;
+$count = @$transcripts;
+pop @$transcripts;
+$transcripts = $gene->get_all_Transcripts;
+cmp_ok(scalar @$transcripts, '==', $count, "Gene's transcript cache is not modified by changing transcript lists in caller code");
+
 ok(scalar(@{$gene->get_all_Exons()}) == 3);
 
 $gene = $gene->transform("chromosome");