The output of `wc -l` on darwin starts with a tab:
git rev-list 266f6548611ad0de93e7470eb13731db819f184b..HEAD | wc -l
0
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
git worktrees have a .git file rather than a .git directory, so building
in a worktree caused version.sh to generate an error.
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>