Appveyor having problems generating version.h

[actual-nh]

Appveyor builds are erroring with:

Get version string
  Done
  Generating "version.h"...
  fatal: not a git repository (or any of the parent directories): .git
  VERSION defined as "Please install `git` to generate VERSION"

at the start. Even if the tests go fine it's still returning as an error, as far as I can tell because of the above.

Steps To Reproduce

See recent pull requests with failures (e.g., #47020, #47021).

Expected behavior

Build for test properly.

Versions and configuration

N/A (Appveyor)

Additional context

Ping: @ZhilkinSerg, @NorseFTX

[actual-nh]

Oops. #47015 had this error in the appveyor build, but it did not result in picking up as an error. Oops!