Unbind the filter Closure from ArchivableFilesFinder to allow the object

to be garbage collected correctly, and the folder closed.

Fixes https://github.com/composer/satis/issues/64 for PHP 5.4

src/Composer/Package/Archiver/ArchivableFilesFinder.php

@@ -52,9 +52,8 @@ class ArchivableFilesFinder extends \FilterIterator
         );
 
         $this->finder = new Finder\Finder();
-        $this->finder
-            ->in($sources)
-            ->filter(function (\SplFileInfo $file) use ($sources, $filters, $fs) {
+
+        $filter = function (\SplFileInfo $file) use ($sources, $filters, $fs) {
             $relativePath = preg_replace(
                 '#^'.preg_quote($sources, '#').'#',
                 '',
@@ -66,7 +65,15 @@ class ArchivableFilesFinder extends \FilterIterator
                 $exclude = $filter->filter($relativePath, $exclude);
             }
             return !$exclude;
-            })
+        };
+
+        if (method_exists($filter, 'bindTo')) {
+            $filter = $filter->bindTo(null);
+        }
+
+        $this->finder
+            ->in($sources)
+            ->filter($filter)
             ->ignoreVCS(true)
             ->ignoreDotFiles(false);