Bug#877024: modemmanager should ask before messing with serial ports

[Ian Jackson <ijackson@chiark.greenend.org.uk>]

Aleksander Morgado writes ("Bug#877024: modemmanager should ask before messing with serial ports"):
> This is part of the discussion we had in the MM mailing list for such
> a solution:
> https://lists.freedesktop.org/archives/modemmanager-devel/2017-September/005917.html

Thanks, this looks constructive.

Of the heuristics in that mail, most seem to me to be very sound
justifications for thinking that the device is safe to probe.

The one big exception is this:

 | * If vid is a known modem vendor (e.g. huawei, zte, sierra, u-blox,
 |  telit....), it's a modem and we probe the tty.

This is a hostage to the future, since of course we don't know what
devices might be manufactured by a particular vendor in the many-years
life of a Debian release.

I guess that if we in Debian don't like that particular heuristic it
would be possible for us to disble just that one ?

I don't understand this one:

 | * If kernel driver of the TTY is option/sierra/qcserial,

but maybe it is OK.

Ian.