Scenario: upstream-moved

The upstream moved, e.g. to another host, and .splice gets its new URL while a commit is still unpushed. The next push sends that commit to the new URL, with its own message and author: the splice's history doesn't depend on its URL.

Monorepo (vendor/a/): cloned at seed, then a local commit, local change, not pushed yet.
Upstream: seed, at $UPSTREAM and, as a copy, at $UPSTREAM-moved.

A splice's history starts at its mount: the newest commit whose parent had no .splice at the path, or one with another id. The id names the splice, not its upstream, so a new URL keeps it, and the commits before the change still belong to the splice. Compare two splices that swap paths, where the id changes, and so does the history. See the design notes.

Output

setup.bash builds this state:

$ build_scenario scenario_upstream_moved

$ git splice log
===  vendor/a (main)
< e859a6b local change  (Test <test@example.com>)

The id stays when the URL changes:

$ id="$(git config --file vendor/a/.splice splice.id)" && git config --file vendor/a/.splice upstream.origin.url "$UPSTREAM-moved" && git commit -q -am "the upstream moved"

$ [ "$(git config --file vendor/a/.splice splice.id)" = "$id" ] && echo "the same id"
the same id

$ git splice fetch vendor/a
ok   vendor/a fetched

local change is still the one commit to push. The URL change itself changes nothing upstream:

$ git splice log
===  vendor/a (main)
< e859a6b local change  (Test <test@example.com>)

$ git splice push vendor/a
ok   vendor/a: pushed e859a6b to main

$ git -C "$UPSTREAM-moved" log --format=%s main
local change
seed

Output​

Output