controllers: remove redundant Repository database lookups BaseRepoController already provides the repository object in c.db_repo (may be None) and BaseController already provides the repository name in c.repo_name (as given in the URL). (Arguably, that's a bad design, and we should revisit that decision in the future. For now, the code just performs slightly better.)

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.