revlog: move file writing to a separate function Moves the code that actually writes to a file to a separate function in revlog.py. This allows extensions to intercept and use the data being written to disk. For example, an extension might want to replicate these writes elsewhere. When cloning the Mercurial repo on /dev/shm with --pull, I see about a 0.3% perf change. It goes from 28.2 to 28.3 seconds.