Handle Group / Namespace HGRC
Historically, the Namespace (Group or User) Mercurial configuration is loaded in Heptapod by a direct inclusion from HGRC files stored in an actual directory hierarchy on the file system. Before upstream switched to hashed storage, this was the actual hierarchy of directories holding the repositories. After the switch to hashed storage, the sole purpose of this hierarchy had become to host these Mercurial configuration files, and was entirely deprecated upstream.
In the 16.4 development cycle, upstream removed the capability to delete a namespace directory from the file system (both in Rails and in Gitaly). We can probably put it back if needed, but it would be better to have HGitaly handle it because all direct accesses to the repositories file system should be removed from the Rails application, as part of the %HGitaly3: fully in charge effort.