Declare branches to be equal?

[Kris Deugau]

I've got a repository that saw moderate use for several years, then the 
project reached a stable point.

I upgraded SVN as I went along, however on my primary dev system I've 
been stuck with a 1.4 client (CentOS 4).

Recently, I've switched to a different system for further development on 
this project, made a number of commits to bring /trunk and 
/branches/stable into sync, and done further development on /trunk.

I'd like to merge my changes from /trunk now, but I'd also like to make 
use of the merge tracking features that have been added since SVN 1.4.

Is there a way to do "svn merge --record-only" that will result in 
/trunk and /branches/stable being considered equivalent and/or fully 
merged as of a given revision?

Historically, some changes have been made first on /trunk, then merged 
to /branches/stable (mostly new development);  others have been made the 
other way around (bugfixes).  :/

I'd like to avoid walking back over the log to explicitly run "svn merge 
--record-only rA:B source dest" for each of these historical merges.

-kgd