gitattributes are not copied in Geo secondary

In GitPushService, we copy the repository's .gitattributes from its default branch to the bare repository info/attributes. On the secondary, we don't do this because this service doesn't run after a fetch for the repo.

We should perhaps consider running a task to run after a fetch, and do this there.

This isn't a serious bug, but because of this you lose some basic functionality with gitattributes on the secondary (e.g. custom highlighting for files).