Double update of versioned file externals corrupting file timestamps

Hi,

we stumbled over an annoying issue with subversion 1.6.11. If we update
a WC with versioned file externals, files where the version is not equal
to the last revision of the file, are double-updated on _every_ update
like this:

[user_at_machine:~/a/test_file_externals]$ svn up
U trunk/combined-src/file1.c

Fetching external item into 'trunk/combined-src/file1.c'
U trunk/combined-src/file1.c
Updated external to revision 4.

Fetching external item into 'trunk/combined-src/file2.c'
Updated external to revision 4.

Updated to revision 6.
[user_at_machine:~/a/test_file_externals]$ svn up
U trunk/combined-src/file1.c

Fetching external item into 'trunk/combined-src/file1.c'
U trunk/combined-src/file1.c
Updated external to revision 4.

Fetching external item into 'trunk/combined-src/file2.c'
Updated external to revision 4.

Updated to revision 6.
[user_at_machine:~/a/test_file_externals]$

Naturally this updates the file timestamps everytime and thus triggers
Makefile actions.

Is this a known issue? Should I file a bug in the issue tracker? Find
attached a FSFS based demo repository showing the bug.

Franz