1.7.x - merge now accesses all files in WC?

Hi,

Running a merge with a 1.7.x build, SVN now seems to access every file under
a given working copy, whereas 1.6.x did not. The following observations have
been made using Process Monitor.

Under 1.6.x, the following file(s) are accessed merging a revision
(modifying bar.txt only):
 - .svn\entries
 - .svn\prop-base\foo.c.svn-base (for files with existing properties)
 - bar.txt

Under 1.7.x, the following file(s) are accessed (merging the same revision
as above):

 - .svn\wc.db
 - Every versioned file in the working copy

I can't see any reason why all these files would need to be accessed. I seem
to recall some discussion about preventing/warning merging into modified
working copies, could this be the cause? I've tried modifying files within
the WC, but the merge still succeeds.

---
Daniel Becroft