The maintainer script apparently runs 'adduser --system' but hardcodes a path under '/home' for the '--home' option or does not use the '--home' option.
The FHS says: /home is a fairly standard concept, but it is clearly a site-specific filesystem. The setup will differ from host to host. Therefore, no program should rely on this location.
Note that passing --no-create-home alone does not solve the issue because home field of passwd file point to a non existing /home subdirectory. Please use adduser --no-create-home --home /nonexistent instead.