[DRE-maint] vagrant-cachier is marked for autoremoval from testing

[Debian testing autoremoval watch]

vagrant-cachier 1.2.1-3 is marked for autoremoval from testing on 2017-09-03

It (build-)depends on packages with these RC bugs:
869164: ruby-net-scp: ruby-net-scp FTBFS: test failures
869174: ruby-net-sftp: FTBFS: ERROR: Test "ruby2.3" failed:   => 142: assert_raises(ArgumentError) { sftp.download("/path/to/remote", StringIO.new, :recursive => true) }