Fixed regression with selfupgrade command, preventing to get a status…

… about the current version when symbolically linked.

Using proper Installer methods to check for symbolical link folder.

system/src/Grav/Console/Gpm/SelfupgradeCommand.php

@@ -99,11 +99,6 @@ protected function serve()
         $remote = $this->upgrader->getRemoteVersion();
         $release = strftime('%c', strtotime($this->upgrader->getReleaseDate()));
 
-        if ($this->isGravSymlinked()) {
-            $this->output->writeln("<red>ATTENTION:</red> Grav is symlinked, cannot upgrade, aborting...");
-            exit;
-        }
-
         if (!$this->upgrader->meetsRequirements()) {
             $this->output->writeln("<red>ATTENTION:</red>");
             $this->output->writeln("   Grav has increased the minimum PHP requirement.");
@@ -120,6 +115,14 @@ protected function serve()
             exit;
         }
 
+        Installer::isValidDestination(GRAV_ROOT . '/system');
+        if (Installer::IS_LINK === Installer::lastErrorCode()) {
+            $this->output->writeln("<red>ATTENTION:</red> Grav is symlinked, cannot upgrade, aborting...");
+            $this->output->writeln('');
+            $this->output->writeln("You are currently running a symbolically linked Grav v" . $local . ". Latest available is v". $remote . ".");
+            exit;
+        }
+
         // not used but preloaded just in case!
         new ArrayInput([]);
 
@@ -256,9 +259,4 @@ public function formatBytes($size, $precision = 2)
 
         return round(pow(1024, $base - floor($base)), $precision) . $suffixes[(int)floor($base)];
     }
-
-    private function isGravSymlinked()
-    {
-        return (is_link(GRAV_ROOT . '/system'));
-    }
 }