This is in fact a copy of https://jira.percona.com/browse/PXB-1274, since it was closed without any reasons and I'm unable to reopen it.
version_check still behaves like a spyware, it's still present in XtraBackup, it's still enabled by default and it has extra run-time dependencies (DBD::mysql). What's even worse, it adds absolutely no value to users. I don't believe it has any value for Percona either.
Seriously, just get rid of the damn thing. If that's too complicated for bureaucratic reasons, at least make it disabled by default, like Percona Toolkit did a long time ago.