Add tests demonstrating undesired behavior with update-ref todos for copied branches

These tests succeed here, but have comments explaining which bits are undesired.
See next commit for a more detailed explanation why.

pkg/integration/tests/branch/rebase_copied_branch.go

@@ -0,0 +1,69 @@
+package branch
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var RebaseCopiedBranch = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Make a copy of a branch, rebase it, check that the original branch is unaffected",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	GitVersion:   AtLeast("2.38.0"),
+	SetupConfig: func(config *config.AppConfig) {
+		config.AppState.GitLogShowGraph = "never"
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.
+			EmptyCommit("master 1").
+			EmptyCommit("master 2").
+			NewBranchFrom("branch1", "master^").
+			EmptyCommit("branch 1").
+			EmptyCommit("branch 2").
+			NewBranch("branch2")
+
+		shell.SetConfig("rebase.updateRefs", "true")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().Lines(
+			Contains("CI * branch 2"),
+			Contains("CI branch 1"),
+			Contains("CI master 1"),
+		)
+
+		t.Views().Branches().
+			Focus().
+			Lines(
+				Contains("branch2").IsSelected(),
+				Contains("branch1"),
+				Contains("master"),
+			).
+			NavigateToLine(Contains("master")).
+			Press(keys.Branches.RebaseBranch).
+			Tap(func() {
+				t.ExpectPopup().Menu().
+					Title(Equals("Rebase 'branch2' onto 'master'")).
+					Select(Contains("Simple rebase")).
+					Confirm()
+			})
+
+		t.Views().Commits().Lines(
+			Contains("CI * branch 2"), // wrong, don't want a star here
+			Contains("CI branch 1"),
+			Contains("CI master 2"),
+			Contains("CI master 1"),
+		)
+
+		t.Views().Branches().
+			Focus().
+			NavigateToLine(Contains("branch1")).
+			PressPrimaryAction()
+
+		t.Views().Commits().Lines(
+			Contains("CI * branch 2"), // wrong, don't want a star here
+			Contains("CI branch 1"),
+			Contains("CI master 2"), // wrong, don't want this commit
+			Contains("CI master 1"),
+		)
+	},
+})