Import from github fails

Summary

See: https://gitlab.com/gitlab-com/support-forum/issues/1441#note_22133931 The Import fails importing a big repository with undefined method '+' for nil:NilClass @ahmadsherif

Steps to reproduce

Try to import github.com/xbmc/xbmc (which you might need rights for)

Expected behavior

The import should end successfully

Actual behavior

It get's stuck due to the undefined method '+' for nil:NilClass

Relevant logs and/or screenshots

@ahmadsherif Might be able to provide those

Output of checks

This bug happens on gitlab.com