When installing a new Debian system using debian-installer and setting a
French locale, a large number of warning messages related to debconf are
visible in tty4 throughout the installation. The messages are similar to
in-target: Argument "27,2727" isn't numeric in multiplication (*) at
/usr/bin/debconf-apt-progress line 168, <STDIN> line 29.
It looks like the French locale causes decimal numbers to be formatted as
"42,1337" instead of "42.1337" when passing data to debconf-apt-progress.
This seems incorrect: format localisation should only be used when
presenting text to humans, not when feeding data to other programs.
These messages are merely annoying, because it's almost impossible to read
the other kind of (more interesting) messages displayed in tty4. On the
other hand, progress bars on the dialog frontend in tty1 do seem to work
normally, despite these messages.
This is using the Debian-installer Stretch Alpha 7 release (which
presumably uses debconf 1.5.59). I was installing with the regular
text-based install, not the graphical one.
This bug looks a bit similar to #729699.