[orca-list] running 3.18.2 and master on ubuntu 16.04

[<prayner unimelb edu au>]

I would like to run orca master on my ubuntu 16.04 laptop. However
after a few past adventures I'm following the first rule of
wing-walking (never let go of something until you've got hold of
something else) so I'd very much like to be able to switch between
versions as simply as possible, ideally
usr/bin/orca --replace
or
usr/local/bin/orca --replace
I've now cloned the new gitlab repositories
gnome-common, atk, at-spi2-core, at-spi2-atk, pyatspi2 and orca
so I think I'm about ready to start the dance with autogen, ninja and
friends.
Last time I tried this something broke so neither the new nor old orca
would work for a while.
At least part of the problem was a new version of user-settings.conf
installed in my .local/share/orca by master which 3.18.2 wouldn't
swallow.
This one I now know to work around.
However, since we're probably replacing other bits of the underlying
at-spi infrastructure there's every chance that something else in the
installation process will break 3.18.2. Murphy's Law being what it is
there's even a chance I won't find out about it until I reboot and
various things get picked up off PYTHONPATH or LD_LIBRARY_PATH for the
first time.
So, with a request to pardon my paranoia, does anyone know of a fairly
safe way, short of building a vm, to test each step of the
installation process to guarantee a fallback?
I'm mainly an emacspeak user so my proposed solution is, for example
m-x shell
sudo make install (for, say gnome-common)
alt-f2 /usr/bin/orca --replace
if that works, proceed to atk etc.
arrive at orca and finally try
alt-f2 /usr/local/bin/orca --replace
that probably won't work but *might* generate a user-settings.conf
I can subsequently edit to make work.
Firstly, does this look feasible?
Secondly, is there any chance of a user-settings.conf that will work
for both 3.18.2 and master, last time I was getting a KeyError when I
tried to run the user preferences module from 3.18.2, only fixed by
removing user-settings.conf.
I'd welcome any pointers from more daring explorers.
thanks
Peter





-- 
Peter Rayner
Clean Air and Urban Landscapes NESP hub <http://www.nespurban.edu.au>
room 343 <http://maps.unimelb.edu.au/parkville/building/200>
School of Earth Sciences, University of Melbourne, 3010, Vic, Australia
tel: work: +61 (0)3 8344 9708; fax: +61 (0)3 8344 7761 
mobile +61 402 752 379, skype: petermorag 
mail-to: prayner unimelb edu au TWITTER: @raynerstrings
google scholar profile <http://scholar.google.com.au/citations?user=H3up71wAAAAJ&hl=en>