Backport upstream's patch to fix a bug in the remove_bad_chars() failing to...

Backport upstream's patch to fix a bug in the remove_bad_chars() failing to reliably filter out illegal characters, allowing execution of arbitrary commands with the rights of the "lp" user, using forged print service announcements on DNS-SD servers

Bug: #1265
Closes: #780267
Fixes: CVE-2015+2265