Unsupported protocol while download tar.gz package

What it worked for me is the following:

1. Update openssl

   sudo apt-get install openssl libssl-dev
   

2. Modify bootstrap file to enable CMAKE_USE_OPENSSL. Replace this line by:

   cmake_options="-DCMAKE_BOOTSTRAP=1 -DCMAKE_USE_OPENSSL=ON"
   

3. Run bootstrap script normally in cmake folder

   /@path_to_cmake/bootstrap
   

The problem may be that the CURL library shipped with CMake isn't build with SSL support by default. I had to compile cmake with:

./bootstrap --system-curl
make
sudo make install

... and that worked, because my system's curl has SSL support.