Code review comment for lp://qastaging/~xnox/ubuntu-release-upgrader/lp1409555

I've now pushes fixes for all open() calls and logging.warn.

The build ends up using system installation of the ubuntu-release-upgrader.... one cannot remove it as the source code has circular depenency on itself (system update-notifier must be installed, which depends on the system ubuntu-release-upgrader)

...

$ sudo rm /usr/lib/python3/dist-packages/DistUpgrade
$ bzr bd

Above two commands make the build complete including the full test suite, in the current branch.

Note that in the pre-build.sh:

 "(cd utils && ./demotions.py utopic vivid > demoted.cfg)"

passes for me on Trusty, but fails on Vivid, which may be related to changes/regressions in vivid's python-apt. However, I believe that is not related to my changes.