Merge branch 'js/name-rev-use-oldest-ref' into maint

"git describe --contains" often made a hard-to-justify choice of
tag to give name to a given commit, because it tried to come up
with a name with smallest number of hops from a tag, causing an old
commit whose close descendant that is recently tagged were not
described with respect to an old tag but with a newer tag.  It did
not help that its computation of "hop" count was further tweaked to
penalize being on a side branch of a merge.  The logic has been
updated to favor using the tag with the oldest tagger date, which
is a lot easier to explain to the end users: "We describe a commit
in terms of the (chronologically) oldest tag that contains the
commit."

* js/name-rev-use-oldest-ref:
  name-rev: include taggerdate in considering the best name

t/t9903-bash-prompt.sh

@@ -107,7 +107,7 @@ test_expect_success 'prompt - describe detached head - contains' '
 '
 
 test_expect_success 'prompt - describe detached head - branch' '
-	printf " ((b1~1))" >expected &&
+	printf " ((tags/t2~1))" >expected &&
 	git checkout b1^ &&
 	test_when_finished "git checkout master" &&
 	(