Determine latest tag using git describe.
Commit 8648db83 relies on `sort -V` which is unavailable on some platforms. Instead just use `git describe` with --abbrev=0 to only output the tag. We still manually compute the distance to avoid the problem mentioned in that commit. Additionally, add Vincent's fix from commit 3b142cea to the stable branch.
Showing with 3 additions and 3 deletions