plataformatec/devise — comment on commit 96f55a7ac7a61effd03a7f43dbbdfb6af8894579
File:  line 0
By josevalim:

@aaronchi Rails needs to boot the app to precompile the assets (for instance, to read the configurations in initializers) and booting causes the routes file to be loaded. It is all part of the booting process.