Merge branch '6.4' into 7.0

* 6.4:
  Skip Twig v3.9-dev for now
  [Validator] Update Dutch (nl) translation
  Update Albanian translations
  [Validator] Update translation
  [FrameworkBundle] Prevent silenced warning by checking if /proc/mount exists
  [VarDumper][PhpUnitBridge] Fix color detection
  prevent throwing NOT_FOUND error when tube is empty
  [Validator] Update missing validator translation for Swedish
  [FrameworkBundle] Fix eager-loading of env vars in ConfigBuilderCacheWarmer
  [Messenger] Fix failing Redis test
  [Validator] Update Italian (it) translations
  [Validator] Missing translations for Hungarian (hu) #53769
  revert to native PHP union types
  [Validator] Missing translations for Russian (ru) #53775
  fix syntax errors on PHP 7

Author: nicolas-grekas

DeprecationErrorHandler.php

@@ -400,29 +400,29 @@ private static function hasColorSupport(): bool
             return false;
         }
 
-        if ('Hyper' === getenv('TERM_PROGRAM')) {
+        // Detect msysgit/mingw and assume this is a tty because detection
+        // does not work correctly, see https://github.com/composer/composer/issues/9690
+        if (!@stream_isatty($stream) && !\in_array(strtoupper((string) getenv('MSYSTEM')), ['MINGW32', 'MINGW64'], true)) {
             return true;
         }
 
-        if (\DIRECTORY_SEPARATOR === '\\') {
-            return (\function_exists('sapi_windows_vt100_support')
-                && sapi_windows_vt100_support(\STDOUT))
-                || false !== getenv('ANSICON')
-                || 'ON' === getenv('ConEmuANSI')
-                || 'xterm' === getenv('TERM');
+        if ('\\' === \DIRECTORY_SEPARATOR && @sapi_windows_vt100_support(\STDOUT)) {
+            return true;
         }
 
-        if (\function_exists('stream_isatty')) {
-            return @stream_isatty(\STDOUT);
+        if ('Hyper' === getenv('TERM_PROGRAM')
+            || false !== getenv('COLORTERM')
+            || false !== getenv('ANSICON')
+            || 'ON' === getenv('ConEmuANSI')
+        ) {
+            return true;
         }
 
-        if (\function_exists('posix_isatty')) {
-            return @posix_isatty(\STDOUT);
+        if ('dumb' === $term = (string) getenv('TERM')) {
+            return false;
         }
 
-        $stat = fstat(\STDOUT);
-
-        // Check if formatted mode is S_IFCHR
-        return $stat ? 0020000 === ($stat['mode'] & 0170000) : false;
+        // See https://github.com/chalk/supports-color/blob/d4f413efaf8da045c5ab440ed418ef02dbb28bf1/index.js#L157
+        return preg_match('/^((screen|xterm|vt100|vt220|putty|rxvt|ansi|cygwin|linux).*)|(.*-256(color)?(-bce)?)$/', $term);
     }
 }