[PATCH 2/3] Add option to disable threading headers

[Josh Triplett <josht@us.ibm.com>]

Add a --no-thread option to disable generation of In-Reply-To and References
headers, normally used to make the second and subsequent mails appear as
replies to the first.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
---
As requested by Johannes Schindelin <johannes.schindelin@gmx.de>.

 Documentation/git-format-patch.txt |    8 +++++++-
 builtin-log.c                      |    5 ++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index 4ca0014..81e3a9a 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -9,7 +9,7 @@ git-format-patch - Prepare patches for e
 SYNOPSIS
 --------
 [verse]
-'git-format-patch' [-n | -k] [-o <dir> | --stdout] [--attach]
+'git-format-patch' [-n | -k] [-o <dir> | --stdout] [--attach] [--no-thread]
 	           [-s | --signoff] [--diff-options] [--start-number <n>]
 		   <since>[..<until>]
 
@@ -35,6 +35,9 @@ they are created in the current working 
 If -n is specified, instead of "[PATCH] Subject", the first line
 is formatted as "[PATCH n/m] Subject".
 
+The generated mails include In-Reply-To and References headers to make
+the second and subsequent patch mails appear as replies to the first
+mail; --no-thread disables this behavior.
 
 OPTIONS
 -------
@@ -63,6 +66,9 @@ OPTIONS
 --attach::
 	Create attachments instead of inlining patches.
 
+--no-thread::
+	Do not add In-Reply-To and References headers to make the
+	second and subsequent mails appear as replies to the first.
 
 CONFIGURATION
 -------------
diff --git a/builtin-log.c b/builtin-log.c
index 9d0cae1..97df715 100644
--- a/builtin-log.c
+++ b/builtin-log.c
@@ -242,6 +242,7 @@ int cmd_format_patch(int argc, const cha
 	int start_number = -1;
 	int keep_subject = 0;
 	int ignore_if_in_upstream = 0;
+	int thread = 1;
 	struct diff_options patch_id_opts;
 	char *add_signoff = NULL;
 	char message_id[1024];
@@ -311,6 +312,8 @@ int cmd_format_patch(int argc, const cha
 			rev.mime_boundary = argv[i] + 9;
 		else if (!strcmp(argv[i], "--ignore-if-in-upstream"))
 			ignore_if_in_upstream = 1;
+		else if (!strcmp(argv[i], "--no-thread"))
+			thread = 0;
 		else
 			argv[j++] = argv[i];
 	}
@@ -373,7 +376,7 @@ int cmd_format_patch(int argc, const cha
 		commit = list[nr];
 		rev.nr = total - nr + (start_number - 1);
 		/* Make the second and subsequent mails replies to the first */
-		if (nr == (total - 2)) {
+		if (thread && nr == (total - 2)) {
 			strncpy(ref_message_id, message_id,
 				sizeof(ref_message_id));
 			ref_message_id[sizeof(ref_message_id)-1] = '\0';
-- 
1.4.1.gf029