Bug#932974: os-prober should disable debug message in release

[Michael Chang <MChang@suse.com>]

Package: os-prober
Version: 1.76
X-Debbugs-CC: cjwatson@ubuntu.com

The os-prober package should be released with all debug message disabled
to align with what other package does. If the debug message provides
any useful information to user, it should be flagged as info not debug
anyway. 

Currently the syslog could be flooded with debug message from os-prober
while running grub-mkconfig, and we find no better way to manage it
except patching grub. For that a patch has been proposed upstream:

https://www.mail-archive.com/grub-devel@gnu.org/msg29038.html

The mainatainer of grub might not want to maintain extra os-prober
specific option and also the usage of OS_PROBER_DISABLE_DEBUG is so
obscure that we don't know if it will be changed in the future, for eg,
with disabling debug message as default in new release.  

So please consider disabling the debug message in release, and also
provide some way to re-enable it. We could still reuse the
OS_PROBER_DISABLE_DEBUG environment varaible to re-enable it, but is
somewhat confusing name for the new context IMHO.

Thanks.