featurens: Ensure RHEL is correctly identified

[joerayme]

When trying to identify various RedHat releases, RHEL was not being
picked up as a centos release because the Oracle Linux regex was too
permissive: it would match any release name with ' Linux
Server release' in the name. By being more restrictive with the Oracle
regex, RHEL is now properly identified.

I don't know why the Oracle regex used such a permissive matcher for the
name but it still passes all the tests by replacing it with the word
'Oracle'.

Fixes #436

[jzelinskie]

@Djelibeybi does this match all possible Oracle Linux versions or are there some that are outliers?

[Djelibeybi]

There are no outliers:

$ docker run --rm -ti oraclelinux:5 cat /etc/oracle-release
Oracle Linux Server release 5.11

$ docker run --rm -ti oraclelinux:6 cat /etc/oracle-release
Oracle Linux Server release 6.9

$ docker run --rm -ti oraclelinux:7 cat /etc/oracle-release
Oracle Linux Server release 7.4

[Djelibeybi]

Also, I'm not sure if other distributions are providing an /etc/os-release file, but we do for our current releases, i.e. Oracle Linux 6:

$ docker run --rm -ti oraclelinux:6 cat /etc/os-release
NAME="Oracle Linux Server"
VERSION="6.9"
ID="ol"
VERSION_ID="6.9"
PRETTY_NAME="Oracle Linux Server 6.9"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:6:9:server"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://bugzilla.oracle.com/"

ORACLE_BUGZILLA_PRODUCT="Oracle Linux 6"
ORACLE_BUGZILLA_PRODUCT_VERSION=6.9
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=6.9

And Oracle Linux 7:

$ docker run --rm -ti oraclelinux:7 cat /etc/os-release
NAME="Oracle Linux Server"
VERSION="7.4"
ID="ol"
VERSION_ID="7.4"
PRETTY_NAME="Oracle Linux Server 7.4"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:7:4:server"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://bugzilla.oracle.com/"

ORACLE_BUGZILLA_PRODUCT="Oracle Linux 7"
ORACLE_BUGZILLA_PRODUCT_VERSION=7.4
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=7.4

Using /etc/os-release may be something to consider because I believe the non-RHEL and derivative distributions also provide this file.

[joerayme]

Is there anything stopping this from being merged? Would you prefer to look at the /etc/os-release file?

[bison]

LGTM. Thanks!

Sorry this took a while.