From what I have seen, this is a DNS block. Anyone not using their ISP's DNS or the DNS of an ISP that has not yet implemented the block will not see them blocked.
Wouldn't a DNS block also require controlling all the ISPs?
All ISP's in India need to be licensed by the government [1]. Non-compliance with this directive puts their license at risk.
I guess they could MITM the connections. Yes you would get certificate errors, but your choice would be to accept the MITM certificate or not visit github at all.
Correct! The domain and protocol are unencrypted, but the path is encrypted.
Most of them are too general for this. I just suspect they were being inconsistent. Look at the trailing `/` in the URLs. Probably they copy-pasted without much thought.