for-each-ref: add split message parts to %(contents:*).

The %(body) placeholder returns the whole body of a tag or
commit, including the signature. However, callers may want
to get just the body without signature, or just the
signature.

Rather than change the meaning of %(body), which might break
some scripts, this patch introduces a new set of
placeholders which break down the %(contents) placeholder
into its constituent parts.

[jk: initial patch by mg, rebased on top of my refactoring
and with tests by me]

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
index 152e695c81..c872b883ba 100644
--- a/Documentation/git-for-each-ref.txt
+++ b/Documentation/git-for-each-ref.txt
@@ -101,9 +101,10 @@ Fields that have name-email-date tuple as its value (`author`,
 `committer`, and `tagger`) can be suffixed with `name`, `email`,
 and `date` to extract the named component.
 
-The first line of the message in a commit and tag object is
-`subject`, the remaining lines are `body`.  The whole message
-is `contents`.
+The complete message in a commit and tag object is `contents`.
+Its first line is `contents:subject`, the remaining lines
+are `contents:body` and the optional GPG signature
+is `contents:signature`.
 
 For sorting purposes, fields with numeric values sort in numeric
 order (`objectsize`, `authordate`, `committerdate`, `taggerdate`).