fix the backup tests

src/test/common.js

@@ -17,6 +17,7 @@ const appdb = require('../appdb.js'),
     rimraf = require('rimraf'),
     settings = require('../settings.js'),
     settingsdb = require('../settingsdb.js'),
+    tasks = require('../tasks.js'),
     userdb = require('../userdb.js'),
     users = require('../users.js');
 
@@ -182,6 +183,7 @@ function setup(done) {
         (done) => mailboxdb.addMailbox(exports.MAILBOX_NAME, DOMAIN.domain, { ownerId: USER.id, ownerType: mail.OWNERTYPE_USER, active: true }, done),
         (done) => mailboxdb.setAliasesForName(exports.MAILBOX_NAME, DOMAIN.domain, [ { name: exports.ALIAS_NAME, domain: DOMAIN.domain} ], done),
 
+        tasks.stopAllTasks,
     ], done);
 }