[Process] fix interpolation of placeholders

Author: nicolas-grekas

src/Symfony/Component/Process/Process.php

@@ -1554,7 +1554,7 @@ private function escapeArgument(string $argument): string
 
     private function replacePlaceholders(string $commandline, array $env)
     {
-        $pattern = '\\' === DIRECTORY_SEPARATOR ? '!%s!' : '${%s}';
+        $pattern = '\\' === DIRECTORY_SEPARATOR ? '!%s!' : '"$%s"';
 
         return preg_replace_callback('/\{\{ ?([_a-zA-Z0-9]++) ?\}\}/', function ($m) use ($pattern, $commandline, $env) {
             if (!isset($env[$m[1]]) || false === $env[$m[1]]) {

src/Symfony/Component/Process/Tests/ProcessTest.php

@@ -1476,10 +1476,10 @@ public function provideEscapeArgument()
 
     public function testPreparedCommand()
     {
-        $p = new Process('echo {{ abc }}DEF');
-        $p->run(null, array('abc' => 'ABC'));
+        $p = new Process(self::$phpBin.' -r \'print_r($argv);\' {{ abc }}DEF');
+        $p->run(null, array('abc' => 'A" B "C'));
 
-        $this->assertSame('ABCDEF', rtrim($p->getOutput()));
+        $this->assertContains('A" B "CDEF', $p->getOutput());
     }
 
     /**