They're mixing an open source project and a proprietary project in one
repository. Per their readme, the proprietary components are in an
enterprise subdirectory. It would be more polite of them to use two
repositories, but it's their project there's nothing wrong with this *per
se*.
"NoLicenseMax
Part of the software is released under Apache 2 license, the other part of
the project has a directory with DRM that limit the number of users that
the open source version can access. They use the word "open source" in the
read me file.
https://github.com/sourcegraph/sourcegraph#license
Here is th