clone_url: simplify the logic - move summary handling of different URLs with/without id to db Drop the half-baked concept of a separate "clone_uri_by_id" - just always use a single template and change back and forth between {repo} and _{repoid} as necessary. Make it clear that clone_uri_tmpl always is passed as argument.

# 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
.