[PATCH/RFC] [git-subtree.sh] Use raw subject and body modifier "%B" instead of "%s%n%n%b" for commit

I don't know if it is the right place to post this patch, I have sended
an email to the original author apenwarr and have no response. According
to <https://github.com/apenwarr/git-subtree/blob/master/THIS-REPO-IS-OBSOLETE>,
this is the place, but <https://github.com/git/git/blob/master/contrib/README> says
different, which is really confusing. Anyway, here I am.

Recently, I imported a foreign git project as a sub directory into a
main repo which I intend to maintain as primary.

Due to the project I imported has its own remote repo which hosted
on the github, I expected after a 'git-subtree.sh split' the newly
generated subtree branch would be exactly identical to the original
branch. Unfortunately, it is not. I have fixed the committer date
and make everything looks the same with the original branch, but
they just did not end up with same commit sha1 hash. Then, I used
`git cat-file -p` to view the raw output of the both commits and
found that the commit generate by git-subtree has a extra 'new-line'
character appended at the end of the subject which causes the problem.

I checked the source and found "%s%n%n%b" were used to generate the
commit message, this works the fine when a commit has a subject as
well as a body, but most of my commits only have a subject under
which condition a extra 'new-line' character is appended.

Instead, a raw subject and body message modifier '%B' should be used.

Though I think this patch should be applied by default, but the mistake
has been there for a long time, applying this patch may cause the patched
git-subtree generate a different branch for those whose subtree branch
has already been generated using the old git-subtree. Maybe this should
be explained in the help or man page, and add a condition check or a
compatible mode somehow.

Techlive Zheng (1):
  subtree.sh: Use raw subject and body modifier "%B" instead of "%s%n%n%b"

 contrib/subtree/git-subtree.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
1.7.11.4

"%s%n%n%b" is not always equal to "%B". If the commit msg does not have
a body, this will append an extra new-line character to the msg title
which would cause the splited commit has a new sha1 hash. In most cases,
this does not matter, but for a project which did not merged using this
script initially, the 'split' command would not genereate the same
commits as the orginal which may cause conflicts.

Signed-off-by: Techlive Zheng <redacted>
---
 contrib/subtree/git-subtree.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 920c664..5598210 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh

@@ -296,7 +296,7 @@ copy_commit()
 	# We're going to set some environment vars here, so
 	# do it in a subshell to get rid of them safely later
 	debug copy_commit "{$1}" "{$2}" "{$3}"
-	git log -1 --pretty=format:'%an%n%ae%n%ad%n%cn%n%ce%n%cd%n%s%n%n%b' "$1" |
+	git log -1 --pretty=format:'%an%n%ae%n%ad%n%cn%n%ce%n%cd%n%B' "$1" |
 	(
 		read GIT_AUTHOR_NAME
 		read GIT_AUTHOR_EMAIL

-- 
1.7.11.4