bug symfony#24115 [FrameworkBundle] Get KERNEL_DIR through $_ENV too for KernelTestCase (yceruto)

This PR was merged into the 2.7 branch.

Discussion
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[FrameworkBundle] Get KERNEL_DIR through $_ENV too for KernelTestCase

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

See symfony#24113

Commits
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cf11fb9 Get KERNEL_DIR through $_ENV too for KernelTestCase

Author: nicolas-grekas

src/Symfony/Bundle/FrameworkBundle/Test/KernelTestCase.php

@@ -105,8 +105,8 @@ private static function getPhpUnitCliConfigArgument()
      */
     protected static function getKernelClass()
     {
-        if (isset($_SERVER['KERNEL_DIR'])) {
-            $dir = $_SERVER['KERNEL_DIR'];
+        if (isset($_SERVER['KERNEL_DIR']) || isset($_ENV['KERNEL_DIR'])) {
+            $dir = isset($_SERVER['KERNEL_DIR']) ? $_SERVER['KERNEL_DIR'] : $_ENV['KERNEL_DIR'];
 
             if (!is_dir($dir)) {
                 $phpUnitDir = static::getPhpUnitXmlDir();