fix(schedule): don’t massage null value

lib/config/migration.js

@@ -214,10 +214,7 @@ function migrateConfig(config) {
         isMigrated = true;
         migratedConfig.baseBranches = is.array(val) ? val : [val];
         delete migratedConfig.baseBranch;
-      } else if (key === 'schedule' && !val) {
+      } else if (key === 'schedule' && val) {
-        isMigrated = true;
-        migratedConfig.schedule = [];
-      } else if (key === 'schedule') {
         // massage to array first
         const schedules = is.string(val) ? [val] : val;
         // split 'and'

lib/workers/branch/schedule.js

@@ -21,6 +21,9 @@ function hasValidTimezone(timezone) {
 
 function hasValidSchedule(schedule) {
   let message;
+  if (!schedule) {
+    return [true];
+  }
   // check if any of the schedules fail to parse
   const hasFailedSchedules = schedule.some(scheduleText => {
     const massagedText = fixShortHours(scheduleText);

test/config/__snapshots__/migration.spec.js.snap

@@ -98,7 +98,7 @@ Object {
       "minor": Object {
         "automerge": true,
       },
-      "schedule": Array [],
+      "schedule": null,
     },
     Object {
       "depTypeList": Array [

test/workers/branch/schedule.spec.js

@@ -14,6 +14,9 @@ describe('workers/branch/schedule', () => {
     beforeEach(() => {
       jest.resetAllMocks();
     });
+    it('returns true for null', () => {
+      expect(schedule.hasValidSchedule(null)[0]).toBe(true);
+    });
     it('returns false for invalid schedule', () => {
       expect(schedule.hasValidSchedule(['foo'])[0]).toBe(false);
     });