git: Block usage of the MSYS2 Git under Windows
Hi all,
Our current setup for calling Git means that MSYS2 Git will be preferred to Windows Git.
MSYS2 Git can process repositories cloned by Windows Git, but not the other way around. This also breaks Cargo's parsing of .git, if patches are applied (as they trigger the creation of a local clone).
This MR fixes the issue by computing the path to Windows Git once and storing it as a constant.
See: https://lore.kernel.org/git/01cf64db-2ff5-4be5-8968-d280ab0ffc50@kdbg.org/