IMHO the status quo is fine.
Most of the time HG gets the merge right on its own.  Some times kdiff3 pops up and asks me to solve the conflict [0].  Rarely something goes wrong so I just revert Misc/NEWS and re-add the entry manually.

> It seems to me that they are much rarer than they were with svn.

I agree -- I think many of us still see merges as something "bad" that should be avoided, while this is generally no longer true with HG (it was with SVN).
A similar argument is "whitespace/PEP8 changes on 3.4 should be avoided because it makes merging changes from 3.3 more difficult".  While it's true that it makes 3.4 diverge from 3.3, IME this doesn't really bother HG and merges usually goes smoothly (there are other arguments against that kind of changes, but I think this is not a very strong one).

[0]: this usually happens when there is an entry in 3.4 only and I'm merging from 3.3.  kdiff3 asks me if it should use the entry I added in 3.3 or the one that is in 3.4, and all I have to do is telling it to keep them both (ctrl+3/ctrl+2).