contrib/hgweb.wsgi

packaging: "make deb" no longer fails

Release 4.7 rationalized the layout of the build scripts.
Unfortunately, while "make docker-ubuntu-*" and "make docker-debian-*" worked as
expected, "make deb" was broken.

Before this change "make deb" was failing with the following error:
    You are not inside a Mercurial repository!

Or, after the latest changes:
    You are inside <fullpath>, which is not the root of a Mercurial repository

Moreover, when "make deb" failed, the cleanup routine deleted the wrong
directory (contrib/packaging/debian instead of <reporoot>/debian) resulting in
a corrupted working copy that needed to be hg revert-ed.

After this change the docker targets continue to work, and the deb one is able
to finish.

# An example WSGI for use with mod_wsgi, edit as necessary
# See https://mercurial-scm.org/wiki/modwsgi for more information

# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"

# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")

# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()

# enable demandloading to reduce startup time
from mercurial import demandimport; demandimport.enable()

from mercurial.hgweb import hgweb
application = hgweb(config)