Commit hashes different between `splitsh-lite` and `git subtree split`

[Blacksmoke16]

I ran into an issue where the hashes are different between this lib and a standard subtree split. This is causing issues when trying to push the changes to a child repos, while using git subtree push works fine.

$ git version
git version 2.34.1

$ splitsh-lite --version
splitsh-lite version v1.0.1

This issue can be reproduced via this script using https://github.com/crystal-manyrepos/two (but also reproduces when using this repo for example):

mkdir mono
cd mono/
git init
touch README.md
git add -A
git commit -m "Initialize mono repo"

git subtree add --prefix=libs/two/ git@github.com:crystal-manyrepos/two.git master

splitsh-lite --scratch --prefix=libs/two && git subtree split --prefix=libs/two

More details below, but it seems like splitsh isn't gathering all the expected commits which results in the hash being different in the end. I'm not using --squash so I don't think it's related to https://github.com/splitsh/lite/issues/15. I actually also tried with that Docker image in that issue and same problem.

Output:

```sh Initialized empty Git repository in /home/george/dev/git/crystal-many/mono/.git/ [master (root-commit) 1a613f0] Initialize mono repo 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 README.md git fetch git@github.com:crystal-manyrepos/two.git master remote: Enumerating objects: 20, done. remote: Counting objects: 100% (20/20), done. remote: Compressing objects: 100% (14/14), done. remote: Total 20 (delta 3), reused 19 (delta 2), pack-reused 0 Unpacking objects: 100% (20/20), 4.01 KiB | 373.00 KiB/s, done. From github.com:crystal-manyrepos/two * branch master -> FETCH_HEAD Added dir 'libs/two' 1 commits created, 5 commits traversed, in 6ms c8f28643a1f9cb160a075e1672addd1a30d63d6b 88ce77827ecd614fcca6e2bbb6983999daab2367 ```

Debug output:

```sh $ splitsh-lite --prefix=libs/two/ --scratch --debug 2021/12/12 10:25:17 Splitting refs/heads/master 2021/12/12 10:25:17 From "libs/two/" to "ROOT" 2021/12/12 10:25:17 Processing commit: 1a613f0abf4fd5ce57a6d7ec2c9e70bef0c61127 2021/12/12 10:25:17 parents: 2021/12/12 10:25:17 newparents: 2021/12/12 10:25:17 Processing commit: 6e5fa9f03d5350ebee79b6899de1072a3dd126e9 2021/12/12 10:25:17 parents: 2021/12/12 10:25:17 newparents: 2021/12/12 10:25:17 Processing commit: 686027d84b670d9fa7861fe9b16c24a79428a2d4 2021/12/12 10:25:17 parents: 6e5fa9f03d5350ebee79b6899de1072a3dd126e9 2021/12/12 10:25:17 newparents: 2021/12/12 10:25:17 Processing commit: 88ce77827ecd614fcca6e2bbb6983999daab2367 2021/12/12 10:25:17 parents: 686027d84b670d9fa7861fe9b16c24a79428a2d4 2021/12/12 10:25:17 newparents: 2021/12/12 10:25:17 Processing commit: 868052990df6cddf09cc35c4bcbf63c4ade5c66c 2021/12/12 10:25:17 parents: 1a613f0abf4fd5ce57a6d7ec2c9e70bef0c61127 88ce77827ecd614fcca6e2bbb6983999daab2367 2021/12/12 10:25:17 newparents: 2021/12/12 10:25:17 tree is: 774bd095bf0c560acd754e6351f389fe2d1451f0 2021/12/12 10:25:17 copy commit "868052990df6cddf09cc35c4bcbf63c4ade5c66c" "774bd095bf0c560acd754e6351f389fe2d1451f0" "" 2021/12/12 10:25:17 newrev is: c8f28643a1f9cb160a075e1672addd1a30d63d6b 1 commits created, 5 commits traversed, in 4ms c8f28643a1f9cb160a075e1672addd1a30d63d6b ```

Git log (master):

```sh $ git log commit 868052990df6cddf09cc35c4bcbf63c4ade5c66c (HEAD -> master) Merge: 1a613f0 88ce778 Author: George Dietrich Date: Sun Dec 12 10:24:46 2021 -0500 Add 'libs/two/' from commit '88ce77827ecd614fcca6e2bbb6983999daab2367' git-subtree-dir: libs/two git-subtree-mainline: 1a613f0abf4fd5ce57a6d7ec2c9e70bef0c61127 git-subtree-split: 88ce77827ecd614fcca6e2bbb6983999daab2367 commit 1a613f0abf4fd5ce57a6d7ec2c9e70bef0c61127 Author: George Dietrich Date: Sun Dec 12 10:24:45 2021 -0500 Initialize mono repo commit 88ce77827ecd614fcca6e2bbb6983999daab2367 Author: George Dietrich Date: Sat Dec 11 23:19:21 2021 -0500 Bump component versions commit 686027d84b670d9fa7861fe9b16c24a79428a2d4 Author: George Dietrich Date: Sat Dec 11 22:39:52 2021 -0500 Add .summary method commit 6e5fa9f03d5350ebee79b6899de1072a3dd126e9 Author: George Dietrich Date: Sat Dec 11 22:39:10 2021 -0500 Initial commit ```

Git log, branch created via splitsh:

```sh $ splitsh-lite --prefix=libs/two/ --scratch --target=refs/heads/splitsh 1 commits created, 5 commits traversed, in 6ms c8f28643a1f9cb160a075e1672addd1a30d63d6b $ git co splitsh $ git log commit c8f28643a1f9cb160a075e1672addd1a30d63d6b (HEAD -> splitsh) Author: George Dietrich Date: Sun Dec 12 10:24:46 2021 -0500 Add 'libs/two/' from commit '88ce77827ecd614fcca6e2bbb6983999daab2367' git-subtree-dir: libs/two git-subtree-mainline: 1a613f0abf4fd5ce57a6d7ec2c9e70bef0c61127 git-subtree-split: 88ce77827ecd614fcca6e2bbb6983999daab2367 ```

Git log, branch created via subtree split:

```sh $ git subtree split -P libs/two -b subtree-split Created branch 'subtree-split' 88ce77827ecd614fcca6e2bbb6983999daab2367 $ git co subtree-split $ git log commit 88ce77827ecd614fcca6e2bbb6983999daab2367 (HEAD -> subtree-split) Author: George Dietrich Date: Sat Dec 11 23:19:21 2021 -0500 Bump component versions commit 686027d84b670d9fa7861fe9b16c24a79428a2d4 Author: George Dietrich Date: Sat Dec 11 22:39:52 2021 -0500 Add .summary method commit 6e5fa9f03d5350ebee79b6899de1072a3dd126e9 Author: George Dietrich Date: Sat Dec 11 22:39:10 2021 -0500 Initial commit ```

[kdambekalns]

Looking at using this (again), and still seeing differences in the hashes. The discussion in #26 indicates the differences are nothing to worry about, eventually.

In case it helps with debugging, here is a screenshot showing where things (start to) differ in my testcase. For this I split the 8.2 branch of https://github.com/neos/flow-development-collection into https://github.com/kdambekalns/flow/tree/8.2-splitsh.

At point (1) the branches have the same "root", up to that point they are identical. Point (2) shows the first commits being different in both branches - the "same" PR being merged. In point (3) the PR branch (red) shows a difference, the merge of neos/flow-development-collection#1919 is missing in the splitsh-lite split…

Here is the original history bit:

One merge commit for neos/flow-development-collection#1917 clearly having the merge of neos/flow-development-collection#1919. The latter is actually empty (no code changes), so maybe it got "optimized away"? Or maybe the equivalent of https://github.com/git/git/commit/dd65a9e5e3b6298e4fa52e21680008e7fd5556ea#diff-59f70cbe935ec223e3df413b94cab740 (as mentioned in #26)?