Why does tomcat 7 startup script overwrite chkconfig settings on yum update?

Issue

• Tomcat 7 RPM provides the startup script /etc/init.d/tomcat

[root@test ~]# yum provides /etc/init.d/tomcat
Loaded plugins: product-id, rhnplugin, search-disabled-repos, security, subscription-manager
This system is receiving updates from RHN Classic or RHN Satellite.
tomcat-7.0.75-1.el6.noarch : Apache Servlet/JSP Engine, RI for Servlet 3.0/JSP 2.2 API
Repo        : epel
Matched from:
Filename    : /etc/init.d/tomcat

• The stock file contains the following chkconfig configuration:

[root@test ~]# grep chkcon /etc/init.d/tomcat
# chkconfig: - 80 20

• The above means that a chkconfig --add tomcat will result in tomcat being added to all runlevels in the "off" value:

[root@test ~]# chkconfig --list tomcat
tomcat          0:off   1:off   2:off   3:off   4:off   5:off   6:off

• However if one modify the chkconfig entry in file /etc/init.d/tomcat script so that, when chkconfig --add tomcat is run, it is automatically in the "on" position in runlevels 2, 3, 4 and 5:

[root@test ~]# grep chkconf /etc/init.d/tomcat
# chkconfig: 2345 80 20
[root@a-app-l-seind03 ~]# chkconfig --list tomcat
tomcat          0:off   1:off   2:on    3:on    4:on    5:on    6:off

• Upgrade from tomcat-7.0.73-1.el6 to 7.0.75-1.el6 version overwrite, the config change as follows.

[root@test ~]# grep chkcon /etc/init.d/tomcat
# chkconfig: - 80 20

• Why does this happen?