Why does Git in Cygwin complain about info/refs not being found?
From the error, it looks like your git clone line was incorrect (it complains about current_posts—which isn't a project—instead of current_content—which is). Try:

git clone http://git.drupal.org/project/current_content.git


You can also do:

git clone git@git.drupal.org:/project/current_content.git


Note that the master branch is the default branch: you don't need to specify it in the clone or afterwards: it'll automatically check it out.