I couldn't reproduce this locally, either with DMD 2.066.1 or with
2.067.0. Maybe there is something odd with the intermediate build files.
Did you try to perform a fresh build using dub build --force.
To test, I was using the http_server example, modified to use the
"win32" configuration. DUB was run from the VisualStudio 2013 x64
command prompt.