Fix for Yosemite (10.10)

10.10 is treated as less than 10.9.5:
```sh
% printf '10.10\n10.9.5\n10.8\n' | sort -g
10.10
10.8
10.9.5
% printf '10.10\n10.9.5\n10.8\n' | sed 's/^10\.//' | sort -g
8
9.5
10
```