1. Open a new Unity project, make sure that you are not logged in into your Unity account
2. Go to "Sign into your Unity ID" window (to do that: Go to Services tab and press "Sign in" OR select Collab dropdown menu and press "Sign in" OR select Account dropdown menu and press "Sign in")
3. Without entering your Credentials, press Sign in and when press Skip
4. Repeat the 2nd/3rd steps repeatedly (change the way on how you reach the "Sign into your Unity ID" window for crash to happen)

Result: After some time (usually 10/20 skips) crash should occur on:

========== OUTPUTTING STACK TRACE ==================

0x0000000141F4E797 (Unity) RestService::HttpTransport::ResponseData::EnqueueBodyData
0x0000000141F496FC (Unity) RestService::SimpleResponse
0x000000014157D5F4 (Unity) RestService::StructuredHandler<RestService::JSONEmpty,UnityErrorInfo,void>::Handle
0x000000014157D726 (Unity) RestService::StructuredHandler<RestService::JSONEmpty,UnityErrorInfo,void>::Handle
0x0000000141F47F19 (Unity) RestService::InvokeHandlerWithDataCleanup
0x00000001409431CA (Unity) BackgroundJobQueue::ExecuteMainThreadJobs
0x0000000140A10372 (Unity) `InitPlayerLoopCallbacks'::`2'::EarlyUpdateExecuteMainThreadJobsRegistrator::Forward
0x000000014148E60C (Unity) Application::TickTimer
0x000000014168FBD1 (Unity) MainMessageLoop
0x0000000141691BBE (Unity) WinMain
0x00000001427DC1A7 (Unity) __scrt_common_main_seh
0x00007FFFE6991FE4 (KERNEL32) BaseThreadInitThunk
0x00007FFFE6D1EF91 (ntdll) RtlUserThreadStart

========== END OF STACKTRACE ===========

Regression introduced in - 2018.1.0a6
Reproducible with - 2018.1.0a7, 2018.1.0a6
Not reproducible with - 2018.1.0a5, 2017.3.0f3
Fix merged in - 2018.3.0a8