Re: [PATCH] subtree.sh: Use raw subject and body modifier "%B" instead of "%s%n%n%b"

greened@obbligato.org writes:

Techlive Zheng [off-list ref] writes:

quoted

"%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

This looks good to me.  I assume this passes all the tests.  Can you add
a test for this bug so we don't regress?  Junio, I am good with this
patch as soon as we get a test for the problem.

I've applied this patch to my working copy but I'm not finding that I
can recreate the original problem when the patch is disabled.

I assumed the scenario you're trying to fix is:

- Make some commit C to project A with a one-line message
- work, commit, work...
- Add project A as a subproject
- work, commit, work...
- Split project A off into a separate repository

After this, commit C with the one-line message in the split-off projet
should have the same hash it had before project A was incorporated as a
subproject.

As I understad it, you saw the post-split commit having a different
hash?

Is that right?  I am not seeing that problem even without your patch.

I want to make sure I understand what the problem is so I can test for
it.

Thanks!

                      -David