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

Author: nicolas-grekas

Constraints/File.php

@@ -168,7 +168,7 @@ private function normalizeBinaryFormat($maxSize)
             $this->maxSize = $matches[1] * $factors[$unit = strtolower($matches[2])];
             $this->binaryFormat = $this->binaryFormat ?? (2 === \strlen($unit));
         } else {
-            throw new ConstraintDefinitionException(sprintf('"%s" is not a valid maximum size.', $this->maxSize));
+            throw new ConstraintDefinitionException(sprintf('"%s" is not a valid maximum size.', $maxSize));
         }
     }
 }

Tests/Constraints/FileValidatorTest.php

@@ -526,5 +526,14 @@ public function uploadedFileErrorProvider()
         return $tests;
     }
 
+    public function testNegativeMaxSize()
+    {
+        $this->expectException(ConstraintDefinitionException::class);
+        $this->expectExceptionMessage('"-1" is not a valid maximum size.');
+
+        $file = new File();
+        $file->maxSize = -1;
+    }
+
     abstract protected function getFile($filename);
 }