CyanogenMod/android — comment on commit 8327388862650b77646d7ae9e633df2bfae3ec9c
File:  line 0
By koush:

Also, since git blobs are immutable, it allows fancy things such as nginx/varnish caching to take place. That way the git servers themselves are never hit. In theory, it should be much more efficient protocol if implemented properly, and Github seems to think so too.
Our build servers agree. They've stopped having sync failures once switching.