I have a few github repos and they have been working fine for the last few months.
However, a few days ago I started getting a strange error when trying to push
and pull
Maybe you have different libcurl.dll versions installed and one of them is overwriting the github one(that does support https).
I don't know what's your OS, but in windows you have to change the PATH settings, so it will point to the right libcurl.dll (do a libcurl search on c:\ to know where is the github one).
In my case it was the Pure Data install that messed up with libcurl.dll from github.
Hope it helps.