All reports of maintainer-script-should-not-use-piuparts-variable for the archive. The extended description of this tag is:
The maintainer script appears to reference one of the PIUPARTS_* variables such as PIUPARTS_TEST or PIUPARTS_PHASE.
These variables are intended to be used by custom piuparts(1) scripts and not by maintainer scripts themselves.
Please remove the references to this variable.
Refer to the piuparts(1) manual page and https://piuparts.debian.org/doc/README.html for details.
This tag has not been emitted in any package tested by Lintian.