Fix meta.git download/preview. Fix #1275

Author: cdujeu

core/src/plugins/meta.git/src/GitManager.php

@@ -136,7 +136,7 @@ public function applyActions(\Psr\Http\Message\ServerRequestInterface $requestIn
                 $command = $git->getCommand("cat-file");
                 $command->setOption("s", true);
                 $command->addArgument($commitId.":".$file);
-                $size = $command->execute();
+                $size = floatval(trim($command->execute()));
 
                 $command = $git->getCommand("show");
                 $command->addArgument($commitId.":".$file);