Thanks for raising this issue Johannes. We've been installing the sysusers.d files for some time, but the residual groupadd and useradd parts of the postinst scripts were never updated.
Will be fixed in the next PCP upload (date TBD).
- Bug#1138692: /var/lib/dpkg/info/pcp.posti... Johannes Schauer Marin Rodrigues
- Bug#1138692: /var/lib/dpkg/info/pcp.... Ken McDonell
