svn 1.4.2: copy + switch problem

Hi to all,

we use a little script to release a new version: basically we have a
trunk with the next major version (say v2.0) and older releases (say
v1.0 and 1.1); to produce release 1.2
we checkout release/1.1, then we merge the relevant changes from
trunk, and finally we execute a script that roughly starts with:

svn cp . "svn://server/repo/release/1.2" --username deploy --password
xxxxx -m "whatever"
svn switch "svn://server/repo/release/1.2"

Usually "svn switch" merges files without any problem (by definition,
they are identical!).
However if the local folder has files "added with history" from
trunk, switch fails (claiming these files have local modifications)

May this be a bug?

--
  The set of solutions is never empty.
  Two solutions together form a new problem.
-- Mycroft Holmes