diff --git a/src/Composer/Repository/ComposerRepository.php b/src/Composer/Repository/ComposerRepository.php
index 975282702..fe2a8787b 100644
--- a/src/Composer/Repository/ComposerRepository.php
+++ b/src/Composer/Repository/ComposerRepository.php
@@ -32,6 +32,7 @@ use Composer\Semver\Constraint\ConstraintInterface;
 use Composer\Semver\Constraint\Constraint;
 use Composer\Semver\Constraint\EmptyConstraint;
 use Composer\Util\Http\Response;
+use Composer\Util\MetadataMinifier;
 
 /**
  * @author Jordi Boggiano <j.boggiano@seld.be>
@@ -631,30 +632,7 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
                     $versions = $response['packages'][$realName];
 
                     if (isset($response['minified']) && $response['minified'] === 'composer/2.0') {
-                        // TODO extract in other method
-                        $expanded = array();
-                        $expandedVersion = null;
-                        foreach ($versions as $versionData) {
-                            if (!$expandedVersion) {
-                                $expandedVersion = $versionData;
-                                $expanded[] = $expandedVersion;
-                                continue;
-                            }
-
-                            // add any changes from the previous version to the expanded one
-                            foreach ($versionData as $key => $val) {
-                                if ($val === '__unset') {
-                                    unset($expandedVersion[$key]);
-                                } else {
-                                    $expandedVersion[$key] = $val;
-                                }
-                            }
-
-                            $expanded[] = $expandedVersion;
-                        }
-
-                        $versions = $expanded;
-                        unset($expanded, $expandedVersion, $versionData);
+                        $versions = MetadataMinifier::expand($versions);
                     }
 
                     $versionsToLoad = array();
diff --git a/src/Composer/Util/MetadataMinifier.php b/src/Composer/Util/MetadataMinifier.php
new file mode 100644
index 000000000..669dab54b
--- /dev/null
+++ b/src/Composer/Util/MetadataMinifier.php
@@ -0,0 +1,78 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Util;
+
+class MetadataMinifier
+{
+    public static function expand(array $versions)
+    {
+        $expanded = array();
+        $expandedVersion = null;
+        foreach ($versions as $versionData) {
+            if (!$expandedVersion) {
+                $expandedVersion = $versionData;
+                $expanded[] = $expandedVersion;
+                continue;
+            }
+
+            // add any changes from the previous version to the expanded one
+            foreach ($versionData as $key => $val) {
+                if ($val === '__unset') {
+                    unset($expandedVersion[$key]);
+                } else {
+                    $expandedVersion[$key] = $val;
+                }
+            }
+
+            $expanded[] = $expandedVersion;
+        }
+
+        return $expanded;
+    }
+
+    public static function minify(array $versions)
+    {
+        $minifiedVersions = array();
+
+        $lastKnownVersionData = null;
+        foreach ($versions as $version) {
+            if (!$lastKnownVersionData) {
+                $lastKnownVersionData = $version;
+                $minifiedVersions[] = $version;
+                continue;
+            }
+
+            $minifiedVersion = [];
+
+            // add any changes from the previous version
+            foreach ($version as $key => $val) {
+                if (!isset($lastKnownVersionData[$key]) || $lastKnownVersionData[$key] !== $val) {
+                    $minifiedVersion[$key] = $val;
+                    $lastKnownVersionData[$key] = $val;
+                }
+            }
+
+            // store any deletions from the previous version for keys missing in current one
+            foreach ($lastKnownVersionData as $key => $val) {
+                if (!isset($version[$key])) {
+                    $minifiedVersion[$key] = "__unset";
+                    unset($lastKnownVersionData[$key]);
+                }
+            }
+
+            $minifiedVersions[] = $minifiedVersion;
+        }
+
+        return $minifiedVersions;
+    }
+}
diff --git a/tests/Composer/Test/Util/MetadataMinifierTest.php b/tests/Composer/Test/Util/MetadataMinifierTest.php
new file mode 100644
index 000000000..ad8d3abad
--- /dev/null
+++ b/tests/Composer/Test/Util/MetadataMinifierTest.php
@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Test\Util;
+
+use Composer\Util\MetadataMinifier;
+use Composer\Package\CompletePackage;
+use Composer\Package\Dumper\ArrayDumper;
+use PHPUnit\Framework\TestCase;
+
+class MetadataMinifierTest extends TestCase
+{
+    public function testMinifyExpand()
+    {
+        $package1 = new CompletePackage('foo/bar', '2.0.0.0', '2.0.0');
+        $package1->setScripts(array('foo' => 'bar'));
+        $package1->setLicense(array('MIT'));
+        $package2 = new CompletePackage('foo/bar', '1.2.0.0', '1.2.0');
+        $package2->setLicense(array('GPL'));
+        $package2->setHomepage('https://example.org');
+        $package3 = new CompletePackage('foo/bar', '1.0.0.0', '1.0.0');
+        $package3->setLicense(array('GPL'));
+        $dumper = new ArrayDumper();
+
+        $minified = array(
+            array('name' => 'foo/bar', 'version' => '2.0.0', 'version_normalized' => '2.0.0.0', 'type' => 'library', 'scripts' => array('foo' => 'bar'), 'license' => array('MIT')),
+            array('version' => '1.2.0', 'version_normalized' => '1.2.0.0', 'license' => array('GPL'), 'homepage' => 'https://example.org', 'scripts' => '__unset'),
+            array('version' => '1.0.0', 'version_normalized' => '1.0.0.0', 'homepage' => '__unset'),
+        );
+
+        $source = array($dumper->dump($package1), $dumper->dump($package2), $dumper->dump($package3));
+
+        $this->assertSame($minified, MetadataMinifier::minify($source));
+        $this->assertSame($source, MetadataMinifier::expand($minified));
+    }
+}