Merge branch 'tr/format-patch-thread'

* tr/format-patch-thread:
  format-patch: support deep threading
  format-patch: thread as reply to cover letter even with in-reply-to
  format-patch: track several references
  format-patch: threading test reactivation

Conflicts:
	builtin-log.c

1 files changed, 9 insertions, 1 deletions

diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index e7ae8cf10..c14e3ee39 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -127,10 +127,18 @@ include::diff-options.txt[]
 	which is the commit message and the patch itself in the
 	second part, with "Content-Disposition: inline".
 
---thread::
+--thread[=<style>]::
 	Add In-Reply-To and References headers to make the second and
 	subsequent mails appear as replies to the first.  Also generates
 	the Message-Id header to reference.
++
+The optional <style> argument can be either `shallow` or `deep`.
+'Shallow' threading makes every mail a reply to the head of the
+series, where the head is chosen from the cover letter, the
+`\--in-reply-to`, and the first patch mail, in this order.  'Deep'
+threading makes every mail a reply to the previous one.  If not
+specified, defaults to the 'format.thread' configuration, or `shallow`
+if that is not set.
 
 --in-reply-to=Message-Id::
 	Make the first mail (or all the mails with --no-thread) appear as a