This was failing on environments that did not have any LANG or LC_* locale
variables set. This is a valid setup, and is common in headless setups, so
it needs to be handled.
This also adds a new pass of the test suite without the locale env vars set
so that this situation is also tests on gitlab-ci, not only gpjenkins.
The error this caused was:
UnicodeEncodeError: 'ascii' codec can't encode characters in position 6-18: ordinal not in range(128)
With the binary transparency log stored in git, it makes that more readable
and as small as possible if the index files are fully sorted. That will
reduce the differences between two copies of an index file to a bare
minimum.
If in the future we implement some kind of binary diff transfer, this will
also help there.
