[ot][journal][personal][crazy] trying to write something clearer :)

[Undescribed Horrific Abuse, One Victim & Survivor of Many]

script visible at
https://github.com/xloem/wheecode/commit/a21120eae018a12d4161991946d57a0a53083055
it's just quick pasta

the three lines of interest are 85, 99, and 114
here are lines 85 and 99:
85: transform=--path-rename="$srcname":"$dstname"
99: git filter-repo $transform --source "$SRC_REPO" --target
"$DST_REPO" --refs "$SRCTIP" --replace-refs update-and-add

i don't like sharing these two lines but they happen prior to the next one.
git-filter-repo is an evil bookburning tool for changing the entirety
of git history such that something was different. in the world wide
web i see, it seems presently recommended by the git project over
git-filter-branch and such. i rename a subfolder into a new repository
and then rebase only the commits of interest.

here's line 114:
114:    MERGE_COMMIT="$(git commit-tree -m "Rebased and merged $1 from
$srcname into $dstname." "$DST_TREE" -p "$DSTTIP" -p "$SRCTIP")"

git commit-tree is a really cool plumbing command for creating a
manual commit. of course, it would be nice if git-merge let you make
arbitrary merge commits itself (it only merges the working tree) but
as a nerd i find internals pretty fun when i have time to engage them.
-m gives the message for the new commit, the positional parameter is
the tree associated with the commit (which I got with `git rev-parse
HEAD^{tree}` where ^{tree} is a magic git suffix that means the tree
rather than the commit) and each -p is a parent for the commit. the
new commit hash is output on stdout.