delta editor: file properties are not preserved during svnsync of subdir

I've attached a file that creates a small repo that you can use to
reproduce this problem.

If you svnsync only the trunk of this repo, the new repo loses the
svn:special and svn:executable properties of files.

I ran into this with hgsubversion, but the bug is within svn itself: the
delta editor's change_file_prop hook is not called in these instances.

Reproduced with 1.6 and 1.7.