To Whom It May Concern.
>> Version 3.3.2 released on January 25th, 2017
>> Version 4.0.0 released on March 3rd, 2017
Note that BackupPC 4.0.0 requires the perl module BackupPC::XS (>= 0.50) and rsync-bpc (>= 184.108.40.206). Those releases are here:
Unfortunately app-backup/backuppc has been without a maintainer for quite a while now. Would you perhaps be interested in becoming its proxied maintainer? You would then be the person responsible for this package, with someone from our dedicated team  committing your work to Portage for you.