Description of problem:

Upgrade path to dosfstools in current devel tree broken.

dosfstools:
  5: 0:2.11-5.FC5 (FC5-updates)
  6: 0:2.11-5 (FC6)

I'd suggest making use of brew's newly added support for the %{?dist} tag, which
is widely used in Extras, like so:

RCS file: /cvs/dist/rpms/dosfstools/devel/dosfstools.spec,v
retrieving revision 1.25
diff -r1.25 dosfstools.spec
4c4
< Release: 5
---
> Release: 5%{?dist}

That would make the next release in the devel tree 2.11-5.fc6, which is
sufficiently rpm-newer to repair the upgrade path.