Code review comment for ~kissiel/plainbox:fix-1262898-warns-when-XFG_HOME-RO

I think this commit broke one debian patch:

Applying patch /home/buildd/build-RECIPEBRANCHBUILD-1515077/chroot-autobuild/home/buildd/work/tree/recipe/debian/patches/silence-logging-failure
patching file plainbox/impl/logging.py
Hunk #1 FAILED at 94.
1 out of 1 hunk FAILED -- rejects in file plainbox/impl/logging.py
Restoring plainbox/impl/logging.py
Patch /home/buildd/build-RECIPEBRANCHBUILD-1515077/chroot-autobuild/home/buildd/work/tree/recipe/debian/patches/silence-logging-failure does not apply (enforce with -f)
Restoring plainbox/impl/logging.py
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/gitbuildrecipe/main.py", line 164, in main
    package_version.upstream_version, working_basedir)
  File "/usr/lib/python3/dist-packages/gitbuildrecipe/deb_util.py", line 86, in extract_upstream_tarball
    raise NoSuchTag(tag_names[0])
gitbuildrecipe.deb_util.NoSuchTag

I'll try to refresh it to restore our daily builds of plainbox