Since commit 71b14dcb (Utilities/Release: Do not upload doc staging
tarball, 2014-02-26) the prefix upload_release.cmake computes does not
match any files when used with -DVERSION=master as has been done for the
nightly binary builds.  Since the version is not actually 'master'
anyway, change the nightly binary upload logic to explicitly pass the
destination directory.  Do not pass any VERSION so the default is taken
and matches the binaries.