pub fn mark_git_unavailable()Expand description
Force the memoized git-availability check to return false for the rest of the session.
Call this when a git invocation fails in a way that indicates the binary
exists on PATH but cannot actually run – the macOS xcrun shim being the
main case (xcrun: error: invalid active developer path). Subsequent
check_git_available() calls then short-circuit to false, so downstream code
that guards on git availability skips cleanly instead of failing repeatedly
with the same exec error.