add OCP\Config:deleteSystemValue

apps/files/appinfo/update.php

@@ -2,7 +2,7 @@
 
 // this drops the keys below, because they aren't needed anymore
 // core related
-if (version_compare(\OC_Config::getValue('version', '0.0.0'), '7.0.0', '<')) {
-	\OC_Config::deleteKey('allowZipDownload');
-	\OC_Config::deleteKey('maxZipInputSize');
+if (version_compare(\OCP\Config::getSystemValue('version', '0.0.0'), '7.0.0', '<')) {
+	\OCP\Config::deleteSystemValue('allowZipDownload');
+	\OCP\Config::deleteSystemValue('maxZipInputSize');
 }

lib/public/config.php

@@ -70,6 +70,16 @@ class Config {
 		return true;
 	}
 
+	/**
+	 * Deletes a value from config.php
+	 * @param string $key key
+	 *
+	 * This function deletes the value from config.php.
+	 */
+	public static function deleteSystemValue( $key ) {
+		return \OC_Config::deleteKey( $key );
+	}
+
 	/**
 	 * Gets the config value
 	 * @param string $app app