The current uname is branch-cXXXX-gHASH
Three changes to make uname more useful.
- Move from using git rev-list --count to git rev-lis --count --first-parent since that gives a better, incrementing number.
- Report this count as 'vXXXXX' rather than 'cXXXXX' because c is part of a hash and we've changed the sematnics of XXXXX
- Remove g to make HASH cut and pastable.