While trying to build opencv:x64-windows, vcpkg repeatedly errors out with this error:

CMake Error at scripts/cmake/vcpkg_download_distfile.cmake:72 (file):
  file problem creating directory:
  D:/downloads/code/visual_studio/vcpkg/downloads/temp
Call Stack (most recent call first):
  scripts/cmake/vcpkg_from_github.cmake:106 (vcpkg_download_distfile)
  ports/eigen3/portfile.cmake:3 (vcpkg_from_github)
  scripts/ports.cmake:72 (include)

This has happened for several dependency of opencv, starting with libjpeg-turbo[core]:x64-windows. Restarting the process, the build will actually succeed for the offending package, only to fail on the next one.

Note that the folder in question is just fine, plenty of space, write permissions etc.

Here's the full list of dependencies that failed on first attempt, and worked on second (in the order the errors occurred):
libjpeg-turbo[core]:x64-windows
tiff[core]:x64-windows
eigen3[core]:x64-windows
opencv[core,eigen,flann,jpeg,opengl,png,tiff]:x64-windows

FWIW, restarting the vcpkg command after the error succeeds after a very long time (~ 10 min., the line 'Building package...' just sits there for many minutes), not sure this is to be expected?

System details:
Win7 x64 english
Command used: vcpkg.exe install opencv:x64-windows
Vcpkg version: 0.0.105-2018-03-16-7528c4d525419a418e8e0046f6650b833ad75fd7