Bigcouch "Error in process (...) with exit value: {{nocatch,conflict} (...)"

I can see this happening many times on cdev:

[Wed, 29 Jan 2014 18:35:05 GMT] [error] [emulator] [--------] Error in process <0.1001.0> on node 'bigcouch@gadwall.cdev.bitmask.net' with exit value: { {nocatch,conflict},[{fabric,update_doc,3,[{file,"src/fabric.erl"},{line,186}]},{chttpd_db,'-update_doc/6-fun-0-',3,[{file,"src/chttpd_db.erl"},{line,786}]}]}

Should check:

• Is this happening on dev and bm.net also?
• What is causing this error?

(from redmine: created on 2014-01-29, closed on 2014-06-03)