[DRE-maint] reel is marked for autoremoval from testing

[Debian testing autoremoval watch]

reel 0.6.1-3 is marked for autoremoval from testing on 2017-01-21

It (build-)depends on packages with these RC bugs:
847450: ruby-celluloid-io: FTBFS randomly (Failed examples: [...] mailbox_spec.rb)