We used to set LC_ALL=C unconditionally when executing a command. This
is a problem if we want the output of a specific command to be
translated (provided a locale definition and an actual translation exist
for the requested language).
This patch adds the clean_locale parameter, which can be used to specify
if we want the locale variable to be cleaned, to most of the helpers
that execute commands.
The value defaults to True so the default behavior is preserved.
If one wants a command to be translated, they have to explicitly pass
clean_locale=False.
Signed-off-by: Olivier Gayot <olivier.gayot@canonical.com>