Comment 4 for bug 674570

Yes, on some distributions both owner and group of /etc/cups/cupsd.conf are "root".
for some distributions owner is "root" and group is "lp"
for example:
Fedora: -rw-r--r-- 1 root lp .....
Ubuntu: -rw-r--r-- 1 root root ....

and the "SystemGroup" attribute values are also varying from one distribution to other distribution.
for example:
ubuntu it is "lpadmin",
Suse it is "sys root",
Fedora it is "sys root",
Debian it is "lpadmin",
here in case of fedora user is required to added to "sys" group and "root" is optional.
and in case of ubuntu user is required to add to "lpadmin"

For instance, in fedora if user is not part of "sys" group. and user part of "lp" group. then while running hp-setup printer will get detect on USB but as user not part of "sys" group. add printer will fail. if we add current user to "sys" group in fedora, we will be able to add printer queue.

With the patch applied on hplip-3.10.9, the patch we will not change the CUPS Configuration file. it read configuration file and detect the groups to which user is required to add.

The patch you are given is working while adding printer on SUSE (even user is not part of "sys", because "SystemGroup" attribute values are "sys root".). as we are telling "root" user by saying cupsSetUser("root") to CUPS server.
But, add printer operation with your patch is failed on Ubuntu. because user is required to add to only "lpadmin" group.
I have tested this on both Suse and Ubuntu.

is this bug report is on RHEL?
and the patch on hplip-3.10.9 has applied only to qt4 platforms. will extent that to qt3 platforms too.

Naga Samrat Chowdary, Narla