В том случае, если в систем нет группы webmaster, то при установке apache-common
она не создаётся.

[root@vm root]# apt-get install apache mod_ssl mod_php
Reading Package Lists... Done
Building Dependency Tree... Done
The following extra packages will be installed:
  apache-common libdb1 libexpat libgdbm libmm openssl perl-DBM php-base 
php-libs
The following NEW packages will be installed:
  apache apache-common libdb1 libexpat libgdbm libmm mod_php mod_ssl openssl 
perl-DBM php-base php-libs
0 upgraded, 12 newly installed, 0 removed and 0 not upgraded.
Need to get 0B/2298kB of archives.
After unpacking 5455kB of additional disk space will be used.
Do you want to continue? [Y/n] y
...skip...
warning: group webmaster does not exist - using root
warning: group webmaster does not exist - using root
...skip...

Steps to Reproduce:
1. Установить в минимальной конфигурации ALM2.4b3, отключив установку всех групп
пакетов.
2. apt-get install apache mod_ssl mod_php