rust: Switch to the memmap2-rs crate
https://github.com/RazrFalcon/memmap2-rs
This is a fork of the original memmap crate which appears to be unmaintained:
https://github.com/danburkert/memmap-rs/issues/90
This fork is the most popular according to https://crates.io/keywords/mmap
Differential Revision: https://phab.mercurial-scm.org/D11397
Ancestors of 5
4 2 0
Ancestors of 6 and 5
4 3 2 1 0
Ancestors of 5 and 4
4 2 0
Ancestors of 7, stop at 6
6
Ancestors of 7, including revs
7 6 5 4 3 2 1 0
Ancestors of 7, 5 and 3, including revs
7 6 5 4 3 2 1 0
Descendants of 5
7 8
Descendants of 5 and 3
6 7 8
Descendants of 5 and 4
5 7 8