Project and Namespace environment variables on hashed storage
When called from the Rails application, the Mercurial process receives information about the current project, passed as environment variables which can in turn be useful to hooks.
We have notably
HEPTAPOD_PROJECT_NAMESPACE_FULL_PATH, the concatenation of which is the relative URI of the project from the server base URL.
The initial implementation was done for #72 (closed), at a time when these paths could be inferred in a very straightforward way from the repository path on the file system. With the hashed storage, the repository file system path has nothing to do with the URI path of the project.