Hardening get-scala-version.

Reimplementing without git-describe to harden against old
gits and make any kind of reference tag unnecessary.

Conflicts:

	tools/get-scala-revision

Author: paulp

tools/get-scala-revision

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+#
+# Usage: get-scala-revision [dir]
+# Figures out current scala revision of a git clone.
+#
+# If no dir is given, current working dir is used.
+
+# not like releases come out so often that we are duty-bound
+# to recalculate this every time.
+# git merge-base v2.9.1 master
+devbase="d6f3184fc8"
+
+# reimplementing git describe hopefully in a way which works
+# without any particular tags, branches, or recent versions of git.
+# this is supposed to generate
+#     dev-NNNN-g<sha>
+# where NNNN is the number of commits since devbase, which
+# is the merge-base of the most recent release and master.
+# Presently hardcoded to reduce uncertainty, v2.9.1/master.
+commits=$(GIT_PAGER=cat git log --oneline $devbase..HEAD | wc -l)
+sha=$(git log -1 --abbrev-commit --abbrev=7 --format="%h")
+printf "dev-%s-g%s\n" $commits $sha