Re: ibrowse queue

[Randall Leeds]

Also, I'm concerned that we cannot rely on couch not to starve the
reader requests while allowing the missing revs requests, leading to
an unbounded growth of the reader queue. The reason for this is that
the reader requests are started with spawn_monitor and therefore
erlang scheduling might give the reader loop time issue the next
couch_rep_missing_revs:next/1 call before any or all of the document
read processes call couch_rep_reader:open_doc_revs/3.