Fixed Travis CI + nextcloud/server#7909

Author: splitt3r

.travis.yml

@@ -15,14 +15,15 @@ addons:
   apt:
     packages:
     - libxml2-utils
+    
 env:
   global:
-    - CORE_BRANCH=master
+    - CORE_BRANCH=stable13
     - APP_NAME=polls
   matrix:
     - DB=mysql
-    - DB=sqlite
     - DB=pgsql
+    - DB=sqlite
 
 cache:
   directories:

lib/Migration/Version009000Date20171202105141.php

@@ -24,7 +24,7 @@
 namespace OCA\Polls\Migration;
 
 use Doctrine\DBAL\Types\Type;
-use OC\DB\SchemaWrapper;
+use OCP\DB\ISchemaWrapper;
 use OCP\Migration\SimpleMigrationStep;
 use OCP\Migration\IOutput;
 
@@ -35,13 +35,13 @@ class Version009000Date20171202105141 extends SimpleMigrationStep {
 
 	/**
 	 * @param IOutput $output
-	 * @param \Closure $schemaClosure The `\Closure` returns a `SchemaWrapper`
+	 * @param \Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
-	 * @return null|SchemaWrapper
+	 * @return null|ISchemaWrapper
 	 * @since 13.0.0
 	 */
 	public function changeSchema(IOutput $output, \Closure $schemaClosure, array $options) {
-		/** @var SchemaWrapper $schema */
+		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();
 
 		if (!$schema->hasTable('polls_events')) {