Add a --cover-letter option to format-patch

If --cover-letter is provided, generate a cover letter message before
the patches, numbered 0.

Original patch thanks to Johannes Schindelin

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 127 insertions, 0 deletions

diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 9eec754221..6b4d1c52bb 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -245,6 +245,7 @@ format-patch --inline --stdout initial..master
 format-patch --inline --stdout --subject-prefix=TESTCASE initial..master
 config format.subjectprefix DIFFERENT_PREFIX
 format-patch --inline --stdout initial..master^^
+format-patch --stdout --cover-letter -n initial..master^
 
 diff --abbrev initial..side
 diff -r initial..side
diff --git a/t/t4013/diff.format-patch_--stdout_--cover-letter_-n_initial..master^ b/t/t4013/diff.format-patch_--stdout_--cover-letter_-n_initial..master^
new file mode 100644
index 0000000000..0151453b73
--- /dev/null
+++ b/t/t4013/diff.format-patch_--stdout_--cover-letter_-n_initial..master^
@@ -0,0 +1,100 @@
+$ git format-patch --stdout --cover-letter -n initial..master^
+From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
+From: C O Mitter <committer@example.com>
+Date: Mon, 26 Jun 2006 00:05:00 +0000
+Subject: [DIFFERENT_PREFIX 0/2] *** SUBJECT HERE ***
+
+*** BLURB HERE ***
+
+A U Thor (2):
+      Second
+      Third
+
+ dir/sub |    4 ++++
+ file0   |    3 +++
+ file1   |    3 +++
+ file2   |    3 ---
+ 4 files changed, 10 insertions(+), 3 deletions(-)
+ create mode 100644 file1
+ delete mode 100644 file2
+
+From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
+From: A U Thor <author@example.com>
+Date: Mon, 26 Jun 2006 00:01:00 +0000
+Subject: [DIFFERENT_PREFIX 1/2] Second
+
+This is the second commit.
+---
+ dir/sub |    2 ++
+ file0   |    3 +++
+ file2   |    3 ---
+ 3 files changed, 5 insertions(+), 3 deletions(-)
+ delete mode 100644 file2
+
+diff --git a/dir/sub b/dir/sub
+index 35d242b..8422d40 100644
+--- a/dir/sub
++++ b/dir/sub
+@@ -1,2 +1,4 @@
+ A
+ B
++C
++D
+diff --git a/file0 b/file0
+index 01e79c3..b414108 100644
+--- a/file0
++++ b/file0
+@@ -1,3 +1,6 @@
+ 1
+ 2
+ 3
++4
++5
++6
+diff --git a/file2 b/file2
+deleted file mode 100644
+index 01e79c3..0000000
+--- a/file2
++++ /dev/null
+@@ -1,3 +0,0 @@
+-1
+-2
+-3
+-- 
+g-i-t--v-e-r-s-i-o-n
+
+
+From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
+From: A U Thor <author@example.com>
+Date: Mon, 26 Jun 2006 00:02:00 +0000
+Subject: [DIFFERENT_PREFIX 2/2] Third
+
+---
+ dir/sub |    2 ++
+ file1   |    3 +++
+ 2 files changed, 5 insertions(+), 0 deletions(-)
+ create mode 100644 file1
+
+diff --git a/dir/sub b/dir/sub
+index 8422d40..cead32e 100644
+--- a/dir/sub
++++ b/dir/sub
+@@ -2,3 +2,5 @@ A
+ B
+ C
+ D
++E
++F
+diff --git a/file1 b/file1
+new file mode 100644
+index 0000000..b1e6722
+--- /dev/null
++++ b/file1
+@@ -0,0 +1,3 @@
++A
++B
++C
+-- 
+g-i-t--v-e-r-s-i-o-n
+
+$
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 6e8b5f4516..ac78752067 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -122,6 +122,32 @@ test_expect_success 'thread in-reply-to' '
 	done
 '
 
+test_expect_success 'thread cover-letter' '
+
+	rm -rf patches/ &&
+	git checkout side &&
+	git format-patch --cover-letter --thread -o patches/ master &&
+	FIRST_MID=$(grep "Message-Id:" patches/0000-* | sed "s/^[^<]*\(<[^>]*>\).*$/\1/") &&
+	for i in patches/0001-* patches/0002-* patches/0003-* 
+	do
+	  grep "References: $FIRST_MID" $i &&
+	  grep "In-Reply-To: $FIRST_MID" $i
+	done
+'
+
+test_expect_success 'thread cover-letter in-reply-to' '
+
+	rm -rf patches/ &&
+	git checkout side &&
+	git format-patch --cover-letter --in-reply-to="<test.message>" --thread -o patches/ master &&
+	FIRST_MID="<test.message>" &&
+	for i in patches/*
+	do
+	  grep "References: $FIRST_MID" $i &&
+	  grep "In-Reply-To: $FIRST_MID" $i
+	done
+'
+
 test_expect_success 'excessive subject' '
 
 	rm -rf patches/ &&