There doesn't seem to be an ETA, but a resp. enhancement request has recently been accepted by the Bitbucket team, and it gathered a notable number of votes already - you might want to watch and vote for the issue as well to guide Atlassian's roadmap in this regard:
Hello! My name is Mark Askew and I am a Premier Support Engineer for products Bitbucket Server/Data Center, Fisheye & Crucible. Today, I want to bring the discussion that Jennifer, Matt, and ...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs