Merge branch '2.8' into 3.4

* 2.8:
  [Console] Don't go past exact matches when autocompleting
  Disable autoloader call on interface_exists check
  [Validator] Fix LazyLoadingMetadataFactory with PSR6Cache for non classname if tested values isn't an existing class

Author: nicolas-grekas

composer.json

@@ -23,7 +23,7 @@
         "symfony/asset": "~2.8|~3.0|~4.0",
         "symfony/dependency-injection": "~2.8|~3.0|~4.0",
         "symfony/finder": "~2.8|~3.0|~4.0",
-        "symfony/form": "^3.4.7|^4.0.7",
+        "symfony/form": "^3.4.9|^4.0.9",
         "symfony/http-foundation": "^3.3.11|~4.0",
         "symfony/http-kernel": "~3.2|~4.0",
         "symfony/polyfill-intl-icu": "~1.0",
@@ -41,7 +41,7 @@
         "symfony/workflow": "~3.3|~4.0"
     },
     "conflict": {
-        "symfony/form": "<3.4.7|<4.0.7,>=4.0",
+        "symfony/form": "<3.4.9|<4.0.9,>=4.0",
         "symfony/console": "<3.4"
     },
     "suggest": {