Merge branch '4.4' into 5.4

* 4.4:
  Fix composer on appveyor
  [PropertyAccess] Fix typo in PropertyAccessor::readProperty() DocBlock
  [VarExporter] Fix exporting objects with readonly properties
  [ExpressionLanguage] Fix matches when the regexp is not valid
  [Messenger] Add mysql indexes back and work around deadlocks using soft-delete
  [Validator] Fix File constraint invalid max size exception message
  [Console] Fix exit status on uncaught exception with negative code

Application.php

@@ -179,7 +179,7 @@ public function run(InputInterface $input = null, OutputInterface $output = null
             $exitCode = $e->getCode();
             if (is_numeric($exitCode)) {
                 $exitCode = (int) $exitCode;
-                if (0 === $exitCode) {
+                if ($exitCode <= 0) {
                     $exitCode = 1;
                 }
             } else {

Tests/ApplicationTest.php

@@ -1172,6 +1172,25 @@ public function testRunDispatchesExitCodeOneForExceptionCodeZero()
         $this->assertTrue($passedRightValue, '-> exit code 1 was passed in the console.terminate event');
     }
 
+    /**
+     * @testWith [-1]
+     *           [-32000]
+     */
+    public function testRunReturnsExitCodeOneForNegativeExceptionCode($exceptionCode)
+    {
+        $exception = new \Exception('', $exceptionCode);
+
+        $application = $this->getMockBuilder(Application::class)->setMethods(['doRun'])->getMock();
+        $application->setAutoExit(false);
+        $application->expects($this->once())
+            ->method('doRun')
+            ->willThrowException($exception);
+
+        $exitCode = $application->run(new ArrayInput([]), new NullOutput());
+
+        $this->assertSame(1, $exitCode, '->run() returns exit code 1 when exception code is '.$exceptionCode);
+    }
+
     public function testAddingOptionWithDuplicateShortcut()
     {
         $this->expectException(\LogicException::class);