fix #10879. Form/File loses files from previous storageId.

Tested Collaboration System, and User Profile Avatar field.

docs/changelog/7.x.x.txt

@@ -12,6 +12,7 @@
  - fixed #10891: Asset manager JSON feed has macros processed
  - fixed #10900: Matrix: Product Listing template
  - fixed #10902: Shelf asset is whiny
+ - fixed #10879: Collaboration System Thread lose attachments
 
 7.7.19
  - fixed #10838: Forwarded forum post email to new CS adds reply to original thread

lib/WebGUI/Form/File.pm

@@ -181,7 +181,7 @@ deleting the file if it was specified.
 
 sub getValue {
 	my $self = shift;
-	my $value = $self->SUPER::getValue(@_);
+	my $value = $self->getOriginalValue;
 	my $storage = WebGUI::Storage->get($self->session,$value);
 	if (defined $storage) {
 		foreach my $file (@{$storage->getFiles}) {