Finally I fixed it myself (check below PR). Just one line code fixed it.
https://github.com/discourse/discourse/pull/4421
Here when we use Regexp without chomp it have some weird last line char. (maybe \n). Without this change initial db migration failing always in Vagrant with == Seed from /vagrant/db/fixtures/500_lounge_category.rb.
Also I am not facing this issue in docker installation. Even in Ubuntu development guide. Only in Vagrant. Weird 
Edit: File are in Windows PC. Maybe that’s the reason