[FIX] Git merge unit tests on buildslaves

With a buildslave user, we had this, because of the commits generated by
merges in tests (ends in CalledprocessError)


*** Please tell me who you are.
(...)
fatal: empty ident  <buildslave@telemaque.(none)> not allowed
[doc] Fixed docstring RST
useful log line in revert()
Development notes for Git shallow clones
[doc] noted that git merging does not work on 1.7
[doc] in devnotes, fixed names of git subcommands
[FIX] apply gevent code since 7.saas~3 + decode 7.saas~X release as (7, X) release instead of (7, 5)
launchpad #1244721: fixed final reporting of upgrade script with python 2.6
buildbot: added pyPdf dep, that's not listed in setup.py (report module)
Providing environments initialization in runtime.session

This needs further testing, in particular with older OpenERP/Odoo versions
Besides, the current Odoo master version that this has been developped
against calls itself 9.0.0 alpha, one needs to check if the problem
exists for the 8.0 branch.

At this point, I'm not really sure of what happens for a script that would
spawn several threads.
[buildbot] added the dep on pyPdf that's needed for report addon
Merge from stable branch (1.8)
gevent script generation backported to version 7.saas~3 and following
Merged support new Odoo API related environments init
Fixed minor pep8 warning
Removed now useless test teardown debug print
launchpad #1208745: don't fail if [paths] if missing in .hg/hgrc
[hg] missing unit test for archive()
Minor pep8 warning
[hg] proper UserError in offline mode if repo dir is missing