name-rev: allow to specify a subpath for --refs option

When an user wants to filter specific ref using the --refs option,
the pattern needs to match the full ref, e.g. --refs=refs/tags/v1.*.

It'd be convenient to specify a subpath of ref pattern.  For
example, --refs=origin/* can find refs/remotes/origin/master by
searching the pattern against its substrings in turn:

  refs/remotes/origin/master
  remotes/origin/master
  origin/master

If it finds a match in a subpath, unambigous part of the ref path will
be removed in the output.

Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-name-rev.txt b/Documentation/git-name-rev.txt
index ad1d146..6b0f1ba 100644
--- a/Documentation/git-name-rev.txt
+++ b/Documentation/git-name-rev.txt
@@ -25,7 +25,8 @@
 	Do not use branch names, but only tags to name the commits
 
 --refs=<pattern>::
-	Only use refs whose names match a given shell pattern.
+	Only use refs whose names match a given shell pattern.  The pattern
+	can be one of branch name, tag name or fully qualified ref name.
 
 --all::
 	List all commits reachable from all refs