The qmailadmin-1.2.1-r1 refers to a CHANGELOG file but its named 'ChangeLog'. The installation will still work so this a just a cosmetic bug. But the file is missing after installation in '/usr/share/doc/qmailadmin-1.2.1-r1' so i think it's worth to fix it.
this has been fixed at least since 1.2.10