PoolBuilder: Ensure alias references get removed when unfixing a locked package

Use the last key + 1 for an index instead of count, since we unset elements somtimes

src/Composer/DependencyResolver/PoolBuilder.php

@@ -200,7 +200,8 @@ class PoolBuilder
 
     private function loadPackage(Request $request, PackageInterface $package, $propagateUpdate = true)
     {
-        $index = count($this->packages);
+        end($this->packages);
+        $index = key($this->packages) + 1;
         $this->packages[] = $package;
 
         if ($package instanceof AliasPackage) {
@@ -348,6 +349,7 @@ class PoolBuilder
             if ($loadedPackage->getName() === $name && $loadedPackage->getRepository() === $request->getLockedRepository()) {
                 $request->unfixPackage($loadedPackage);
                 unset($this->packages[$i]);
+                unset($this->aliasMap[spl_object_hash($loadedPackage)]);
             }
         }
 

tests/Composer/Test/Fixtures/installer/update-allow-list-with-dependencies-alias.test

@@ -0,0 +1,48 @@
+--TEST--
+Require a new package in the composer.json and updating with its name as an argument and with-dependencies should update locked dependencies as far as possible
+--COMPOSER--
+{
+    "repositories": [
+        {
+            "type": "package",
+            "package": [
+                { "name": "current/pkg", "version": "1.0.0", "require": { "current/dep": "<1.2.0" } },
+                { "name": "current/pkg", "version": "1.1.0", "require": { "current/dep": "^1.0" } },
+                { "name": "current/dep", "version": "1.0.0" },
+                { "name": "current/dep", "version": "1.1.0" },
+                { "name": "current/dep", "version": "1.2.0" },
+                { "name": "new/pkg", "version": "1.0.0", "require": { "current/dep": "^1.1" } },
+                { "name": "new/pkg", "version": "1.1.0", "require": { "current/dep": "^1.2" } }
+            ]
+        }
+    ],
+    "require": {
+        "current/pkg": "1.*",
+        "new/pkg": "1.*"
+    }
+}
+--INSTALLED--
+[
+    { "name": "current/pkg", "version": "1.0.0", "require": { "current/dep": "<1.2.0" } },
+    { "name": "current/dep", "version": "1.0.0" }
+]
+--LOCK--
+{
+    "packages": [
+        { "name": "current/pkg", "version": "1.0.0", "require": { "current/dep": "<1.2.0" } },
+        { "name": "current/dep", "version": "1.0.0" }
+    ],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "dev",
+    "stability-flags": [],
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": [],
+    "platform-dev": []
+}
+--RUN--
+update new/pkg --with-dependencies
+--EXPECT--
+Upgrading current/dep (1.0.0 => 1.1.0)
+Installing new/pkg (1.0.0)