Fixed PoolBuilder running endlessly when packages do not exist

src/Composer/DependencyResolver/PoolBuilder.php

@@ -249,6 +249,8 @@ class PoolBuilder
             $this->loadedNames[$name] = $constraint;
         }
 
+        $preLoad = $this->packagesToLoad;
+
         foreach ($repositories as $repository) {
             if (empty($this->packagesToLoad)) {
                 break;
@@ -271,9 +273,11 @@ class PoolBuilder
         }
 
         // Make sure we empty the packagesToLoad here as it would result
-        // in an endless loop with non-existent packages for example
-        // TODO: fixme, this should only happen if it's not a new package
-        // $this->packagesToLoad = array();
+        // in an endless loop if the array remains unchanged.
+        // This could happen with non-existent packages for example.
+        if ($preLoad == $this->packagesToLoad) {
+            $this->packagesToLoad = array();
+        }
     }
 
     private function loadPackage(Request $request, PackageInterface $package, $propagateUpdate = true)

tests/Composer/Test/DependencyResolver/Fixtures/poolbuilder/packages-that-do-not-exist.test

@@ -0,0 +1,25 @@
+--TEST--
+Test irrelevant package versions are not loaded
+
+--REQUEST--
+{
+    "require": {
+        "root/req": "*"
+    }
+}
+
+--FIXED--
+[
+]
+
+--PACKAGES--
+[
+    {"name": "root/req", "version": "1.0.0", "require": {"dep/dep": "2.*"}},
+    {"name": "dep/dep", "version": "2.3.4", "require": {"dep/dep3": "2.*"}}
+]
+
+--EXPECT--
+[
+    "root/req-1.0.0.0",
+    "dep/dep-2.3.4.0"
+]