Merge branch '3.2'

* 3.2: (24 commits)
  [Filesystem] Remove extra argv in dumpFile() tests
  [DI] minor FileLoaders tests update
  [FrameworkBundle] Add framework.cache.prefix_seed for predictible cache key prefixes
  [SecurityBundle] Remove FirewallContext mandatory FirewallConfig argument deprecation
  [HttpKernel] Revert BC breaking change of Request::isMethodSafe()
  [DI] Allow null as default env value
  [WebProfilerBundle] Fix deprecated uses of profiler_dump
  [SecurityBundle] Fix FirewallConfig nullable arguments
  [FrameworkBundle] Avoid warming up the validator cache for non-existent classes
  [DOMCrawler] Bug fixed
  [FrameworkBundle] Mark cache.default_*_provider services private
  [Process] Do feat test before enabling TTY mode
  bumped Symfony version to 3.1.8
  updated VERSION for 3.1.7
  updated CHANGELOG for 3.1.7
  bumped Symfony version to 2.8.15
  updated VERSION for 2.8.14
  updated CHANGELOG for 2.8.14
  bumped Symfony version to 2.7.22
  updated VERSION for 2.7.21
  ...

Author: fabpot

Crawler.php

@@ -930,7 +930,7 @@ public static function xpathLiteral($s)
             }
         }
 
-        return sprintf('concat(%s)', implode($parts, ', '));
+        return sprintf('concat(%s)', implode(', ', $parts));
     }
 
     /**