./setup.sh should fail when a dependency is missing

[Vincent Ladeuil]

After updating trunk, I attempted to re-create my venv without updating the deps branch.

Since new deps were introduced since my last update, the deps branch was missing the newly introduced deps.

Yet, ./setup.sh succeeded instead of failing when the dep was missing:

== Setting up ticket_system ....
running develop
CI_DEPS_BRANCH(lp:~canonical-ci-engineering/uci-engine/deps) requested at /home/vila/ci/uci-engine/.deps
local deps exist, checking for updates
Using saved parent location: bzr+ssh://bazaar.launchpad.net/~canonical-ci-engineering/uci-engine/deps
No revisions or tags to pull.
HPSS calls: 12 (0 vfs) SmartSSHClientMedium(bzr+ssh://<email address hidden>/)
running egg_info
writing dependency_links to ticket_system.egg-info/dependency_links.txt
writing requirements to ticket_system.egg-info/requires.txt
writing ticket_system.egg-info/PKG-INFO
writing top-level names to ticket_system.egg-info/top_level.txt
reading manifest file 'ticket_system.egg-info/SOURCES.txt'
writing manifest file 'ticket_system.egg-info/SOURCES.txt'
running build_ext
Creating /home/vila/ci/uci-engine/bugs/1331989-homeless/.venv/lib/python2.7/site-packages/ticket-system.egg-link (link to .)
Adding ticket-system 0.1 to easy-install.pth file

Installed /home/vila/ci/uci-engine/bugs/1331989-homeless/ticket_system
Processing dependencies for ticket-system==0.1
Searching for django-openid-auth==0.2
Couldn't find index page for 'django-openid-auth' (maybe misspelled?)
Scanning index of all packages (this may take a while)
No local packages or download links found for django-openid-auth==0.2
error: Could not find suitable distribution for Requirement.parse('django-openid-auth==0.2')