Avoid throwing when checking for disk space, fixes #2039

src/Composer/Command/DiagnoseCommand.php

@@ -219,8 +219,8 @@ EOT
     private function checkDiskSpace($config)
     {
         $minSpaceFree = 1024*1024;
-        if ((($df = disk_free_space($dir = $config->get('home'))) !== false && $df < $minSpaceFree)
-            || (($df = disk_free_space($dir = $config->get('vendor-dir'))) !== false && $df < $minSpaceFree)
+        if ((($df = @disk_free_space($dir = $config->get('home'))) !== false && $df < $minSpaceFree)
+            || (($df = @disk_free_space($dir = $config->get('vendor-dir'))) !== false && $df < $minSpaceFree)
         ) {
             return '<error>The disk hosting '.$dir.' is full</error>';
         }

src/Composer/Console/Application.php

@@ -152,8 +152,8 @@ class Application extends BaseApplication
                 $config = $composer->getConfig();
 
                 $minSpaceFree = 1024*1024;
-                if ((($df = disk_free_space($dir = $config->get('home'))) !== false && $df < $minSpaceFree)
-                    || (($df = disk_free_space($dir = $config->get('vendor-dir'))) !== false && $df < $minSpaceFree)
+                if ((($df = @disk_free_space($dir = $config->get('home'))) !== false && $df < $minSpaceFree)
+                    || (($df = @disk_free_space($dir = $config->get('vendor-dir'))) !== false && $df < $minSpaceFree)
                 ) {
                     $output->writeln('<error>The disk hosting '.$dir.' is full, this may be the cause of the following exception</error>');
                 }