switch from tag with externals to a trunk without can put wc into inconsistent state

Hello,

This is the state of my working copy after I've isolated the bug:
$ svn up
At revision 2.
$ svn st
$ ls top
sub1
$ svn ls top
sub1/
sub2/

It seems bogus and was caused by switching from a tag back to trunk.
Tag has top/sub2/ set to point to the same directory in trunk via
svn:externals Test script is attached. Looks like svn:externals in
this case should be handled before updating files to allow switch to
proceed.

Is there a bug report for this behaviour or is it something new?
svn, version 1.6.4 (r38063)
   compiled Aug 18 2009, 07:56:06

Debian 5.0

Please, CC.

-- 
anatoly t.
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