bug #19908 [Config] Handle open_basedir restrictions in FileLocator (Nicofuma)

This PR was submitted for the 2.8 branch but it was merged into the 2.7 branch instead (closes #19908).

Discussion
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[Config] Handle open_basedir restrictions in FileLocator

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
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e870819 [Config] Handle open_basedir restrictions in FileLocator

Author: fabpot

src/Symfony/Component/Config/FileLocator.php

@@ -57,7 +57,7 @@ public function locate($name, $currentPath = null, $first = true)
         $filepaths = array();
 
         foreach ($paths as $path) {
-            if (file_exists($file = $path.DIRECTORY_SEPARATOR.$name)) {
+            if (@file_exists($file = $path.DIRECTORY_SEPARATOR.$name)) {
                 if (true === $first) {
                     return $file;
                 }