msys2.txt

1. download installer:
http://repo.msys2.org/distrib/x86_64/msys2-x86_64-20190524.exe

2. add repo:
directory: msys64\etc\pacman.d, add following content in the begin of every file.
  file: /etc/pacman.d/mirrorlist.mingw32：
    Server = https://mirrors.tuna.tsinghua.edu.cn/msys2/mingw/i686
  file: /etc/pacman.d/mirrorlist.mingw64：
    Server = https://mirrors.tuna.tsinghua.edu.cn/msys2/mingw/x86_64
  file: /etc/pacman.d/mirrorlist.msys：
    Server = https://mirrors.tuna.tsinghua.edu.cn/msys2/msys/$arch

  file: mirrorlist.msys
    Server = http://mirrors.ustc.edu.cn/msys2/msys/$arch/
  file: mirrorlist.mingw64
    Server = http://mirrors.ustc.edu.cn/msys2/mingw/x86_64/
  file: mirrorlist.mingw32
    Server = http://mirrors.ustc.edu.cn/msys2/mingw/i686/

3. add git

3.1 add following content to /etc/pacman.conf:
  [git-for-windows]
  SigLevel = Optional TrustAll
  Server = https://wingit.blob.core.windows.net/x86-64
NOTE: the msys2 use Windows env %HOME%, so maybe we need change it by set env when starting msys.

3.2 update and installl git
  pacman -Sy
  pacman -S mingw-w64-x86_64-git