diff --git a/src/Composer/Command/SelfUpdateCommand.php b/src/Composer/Command/SelfUpdateCommand.php
index ea0831818..54750d4ad 100644
--- a/src/Composer/Command/SelfUpdateCommand.php
+++ b/src/Composer/Command/SelfUpdateCommand.php
@@ -425,7 +425,14 @@ TAGSPUBKEY
         }
 
         try {
-            rename($newFilename, $localFilename);
+            if (Platform::isWindows()) {
+                // use copy to apply permissions from the destination directory
+                // as rename uses source permissions and may block other users
+                copy($newFilename, $localFilename);
+                @unlink($newFilename);
+            } else {
+                rename($newFilename, $localFilename);
+            }
 
             return true;
         } catch (\Exception $e) {
@@ -534,7 +541,7 @@ TAGSPUBKEY
     /**
      * Invokes a UAC prompt to update composer.phar as an admin
      *
-     * Uses a .vbs script to elevate and run the cmd.exe move command.
+     * Uses a .vbs script to elevate and run the cmd.exe copy command.
      *
      * @param  string $localFilename The composer.phar location
      * @param  string $newFilename   The downloaded or backup phar
@@ -560,13 +567,13 @@ TAGSPUBKEY
 
         $checksum = hash_file('sha256', $newFilename);
 
-        // cmd's internal move is fussy about backslashes
+        // cmd's internal copy is fussy about backslashes
         $source = str_replace('/', '\\', $newFilename);
         $destination = str_replace('/', '\\', $localFilename);
 
         $vbs = <<<EOT
 Set UAC = CreateObject("Shell.Application")
-UAC.ShellExecute "cmd.exe", "/c move /y ""$source"" ""$destination""", "", "runas", 0
+UAC.ShellExecute "cmd.exe", "/c copy /b /y ""$source"" ""$destination""", "", "runas", 0
 Wscript.Sleep(300)
 EOT;
 
@@ -574,11 +581,12 @@ EOT;
         exec('"'.$script.'"');
         @unlink($script);
 
-        // see if the file was moved
-        if ($result = (hash_file('sha256', $localFilename) === $checksum)) {
+        // see if the file was moved and is still accessible
+        if ($result = is_readable($localFilename) && (hash_file('sha256', $localFilename) === $checksum)) {
             $io->writeError('<info>Operation succeeded.</info>');
+            @unlink($newFilename);
         } else {
-            $io->writeError('<error>Operation failed (file not written). '.$helpMessage.'</error>');
+            $io->writeError('<error>Operation failed.'.$helpMessage.'</error>');
         }
 
         return $result;
diff --git a/src/Composer/Downloader/GitDownloader.php b/src/Composer/Downloader/GitDownloader.php
index d45684ef9..78270f4da 100644
--- a/src/Composer/Downloader/GitDownloader.php
+++ b/src/Composer/Downloader/GitDownloader.php
@@ -519,7 +519,7 @@ class GitDownloader extends VcsDownloader implements DvcsDownloaderInterface
     {
         $path = $this->normalizePath($path);
         if (0 !== $this->process->execute('git clean -df && git reset --hard', $output, $path)) {
-            throw new \RuntimeException("Could not reset changes\n\n:".$this->process->getErrorOutput());
+            throw new \RuntimeException("Could not reset changes\n\n:".$output);
         }
 
         $this->hasDiscardedChanges[$path] = true;
@@ -533,7 +533,7 @@ class GitDownloader extends VcsDownloader implements DvcsDownloaderInterface
     {
         $path = $this->normalizePath($path);
         if (0 !== $this->process->execute('git stash --include-untracked', $output, $path)) {
-            throw new \RuntimeException("Could not stash changes\n\n:".$this->process->getErrorOutput());
+            throw new \RuntimeException("Could not stash changes\n\n:".$output);
         }
 
         $this->hasStashedChanges[$path] = true;
@@ -547,7 +547,7 @@ class GitDownloader extends VcsDownloader implements DvcsDownloaderInterface
     {
         $path = $this->normalizePath($path);
         if (0 !== $this->process->execute('git diff HEAD', $output, $path)) {
-            throw new \RuntimeException("Could not view diff\n\n:".$this->process->getErrorOutput());
+            throw new \RuntimeException("Could not view diff\n\n:".$output);
         }
 
         $this->io->writeError($output);
diff --git a/src/Composer/Util/Http/CurlDownloader.php b/src/Composer/Util/Http/CurlDownloader.php
index 5e9494aed..7e4753496 100644
--- a/src/Composer/Util/Http/CurlDownloader.php
+++ b/src/Composer/Util/Http/CurlDownloader.php
@@ -183,7 +183,6 @@ class CurlDownloader
         }
 
         $options['http']['header'] = $this->authHelper->addAuthenticationHeader($options['http']['header'], $origin, $url);
-        // Merge in headers - we don't get any proxy values
         $options = StreamContextFactory::initOptions($url, $options, true);
 
         foreach (self::$options as $type => $curlOptions) {
diff --git a/src/Composer/Util/Http/ProxyHelper.php b/src/Composer/Util/Http/ProxyHelper.php
index 4ca7a4bc8..e291f5b81 100644
--- a/src/Composer/Util/Http/ProxyHelper.php
+++ b/src/Composer/Util/Http/ProxyHelper.php
@@ -131,12 +131,14 @@ class ProxyHelper
         $error = sprintf('malformed %s url', $envName);
         $proxy = parse_url($proxyUrl);
 
+        // We need parse_url to have identified a host
         if (!isset($proxy['host'])) {
             throw new \RuntimeException($error);
         }
 
         $proxyUrl = self::formatParsedUrl($proxy, true);
 
+        // We need a port because streams and curl use different defaults
         if (!parse_url($proxyUrl, PHP_URL_PORT)) {
             throw new \RuntimeException($error);
         }
diff --git a/src/Composer/Util/RemoteFilesystem.php b/src/Composer/Util/RemoteFilesystem.php
index ea899b312..8b8e0c3e0 100644
--- a/src/Composer/Util/RemoteFilesystem.php
+++ b/src/Composer/Util/RemoteFilesystem.php
@@ -254,7 +254,7 @@ class RemoteFilesystem
 
         $ctx = StreamContextFactory::getContext($fileUrl, $options, array('notification' => array($this, 'callbackGet')));
 
-        $proxy = ProxyManager::getInstance()->getProxyForRequest($fileUrl);
+        $proxy = $this->proxyManager->getProxyForRequest($fileUrl);
         $usingProxy = $proxy->getFormattedUrl(' using proxy (%s)');
         $this->io->writeError((strpos($origFileUrl, 'http') === 0 ? 'Downloading ' : 'Reading ') . Url::sanitize($origFileUrl) . $usingProxy, true, IOInterface::DEBUG);
         unset($origFileUrl, $proxy, $usingProxy);
diff --git a/tests/Composer/Test/AllFunctionalTest.php b/tests/Composer/Test/AllFunctionalTest.php
index a901617f9..86e03f9e8 100644
--- a/tests/Composer/Test/AllFunctionalTest.php
+++ b/tests/Composer/Test/AllFunctionalTest.php
@@ -78,7 +78,7 @@ class AllFunctionalTest extends TestCase
             }
         }
 
-        $proc = new Process('php -dphar.readonly=0 '.escapeshellarg('./bin/compile'), $target);
+        $proc = new Process((defined('PHP_BINARY') ? escapeshellcmd(PHP_BINARY) : 'php').' -dphar.readonly=0 '.escapeshellarg('./bin/compile'), $target);
         $exitcode = $proc->run();
 
         if ($exitcode !== 0 || trim($proc->getOutput())) {
@@ -110,7 +110,7 @@ class AllFunctionalTest extends TestCase
             'COMPOSER_CACHE_DIR' => $this->testDir.'cache',
         );
 
-        $cmd = 'php '.escapeshellarg(self::$pharPath).' --no-ansi '.$testData['RUN'];
+        $cmd = (defined('PHP_BINARY') ? escapeshellcmd(PHP_BINARY) : 'php') .' '.escapeshellarg(self::$pharPath).' --no-ansi '.$testData['RUN'];
         $proc = new Process($cmd, $this->testDir, $env, null, 300);
         $output = '';