Mercurial on AppEngine
You need to generate hg.zip, which is done using build_hg_zip.sh in scripts.
This should be run from the root of the working copy, and you should have
a clone of Mercurial in $(hg root)/hg. If in doubt:
$ hg clone http://hg.intevation.org/mercurial/crew hg
$ bash scripts/build_hg_zip.sh
The script applies one minor patch to the hg codebase in order to allow
imports to go through (differences between AppEngine and cPython's httplib)
and moves the "pure" variants of modules into the proper locations.
After that, run `dev_appserver.py .` and navigate to http://localhost:8080/_dash/
and you should get the administrative dashboard.