Dont auto-forward branches that are checked out in another worktree (#4833)

### PR Description

This is similar to #2957, except that in that case it was about an
explicit fast-forward command, and we solved it by doing the
fast-forward in the other work-tree (so that it would fail if that
worktree had modified files, for example). In this case it is about the
relatively new auto-forward feature (added in v0.50, see #4493), and in
this case we fix it by not even trying to auto-forward any branches that
are checked out by other worktrees.

pkg/gui/controllers/helpers/branches_helper.go

@@ -283,7 +283,9 @@ func (self *BranchesHelper) AutoForwardBranches() error {
 	updateCommands := ""
 	// The first branch is the currently checked out branch; skip it
 	for _, branch := range branches[1:] {
-		if branch.RemoteBranchStoredLocally() && (allBranches || lo.Contains(self.c.UserConfig().Git.MainBranches, branch.Name)) {
+		if branch.RemoteBranchStoredLocally() &&
+			!self.checkedOutByOtherWorktree(branch) &&
+			(allBranches || lo.Contains(self.c.UserConfig().Git.MainBranches, branch.Name)) {
 			isStrictlyBehind := branch.IsBehindForPull() && !branch.IsAheadForPull()
 			if isStrictlyBehind {
 				updateCommands += fmt.Sprintf("update %s %s %s\n", branch.FullRefName(), branch.FullUpstreamRefName(), branch.CommitHash)

pkg/integration/tests/sync/fetch_and_auto_forward_branches_all_branches_checked_out_in_other_worktree.go

@@ -0,0 +1,57 @@
+package sync
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var FetchAndAutoForwardBranchesAllBranchesCheckedOutInOtherWorktree = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Fetch from remote and auto-forward branches with config set to 'allBranches'; check that this skips branches checked out by another worktree",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+		config.GetUserConfig().Git.AutoForwardBranches = "allBranches"
+		config.GetUserConfig().Git.LocalBranchSortOrder = "alphabetical"
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateNCommits(3)
+		shell.NewBranch("feature")
+		shell.NewBranch("diverged")
+		shell.CloneIntoRemote("origin")
+		shell.SetBranchUpstream("master", "origin/master")
+		shell.SetBranchUpstream("feature", "origin/feature")
+		shell.SetBranchUpstream("diverged", "origin/diverged")
+		shell.Checkout("master")
+		shell.HardReset("HEAD^")
+		shell.Checkout("feature")
+		shell.HardReset("HEAD~2")
+		shell.Checkout("diverged")
+		shell.HardReset("HEAD~2")
+		shell.EmptyCommit("local")
+		shell.NewBranch("checked-out")
+
+		shell.AddWorktreeCheckout("master", "../linked-worktree")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Branches().
+			Lines(
+				Contains("checked-out").IsSelected(),
+				Contains("diverged ↓2↑1"),
+				Contains("feature ↓2").DoesNotContain("↑"),
+				Contains("master (worktree) ↓1").DoesNotContain("↑"),
+			)
+
+		t.Views().Files().
+			IsFocused().
+			Press(keys.Files.Fetch)
+
+		// AutoForwardBranches is "allBranches": both master and feature get forwarded
+		t.Views().Branches().
+			Lines(
+				Contains("checked-out").IsSelected(),
+				Contains("diverged ↓2↑1"),
+				Contains("feature ✓"),
+				Contains("master (worktree) ↓1"),
+			)
+	},
+})

pkg/integration/tests/test_list.go

@@ -383,6 +383,7 @@ var tests = []*components.IntegrationTest{
 	submodule.Reset,
 	submodule.ResetFolder,
 	sync.FetchAndAutoForwardBranchesAllBranches,
+	sync.FetchAndAutoForwardBranchesAllBranchesCheckedOutInOtherWorktree,
 	sync.FetchAndAutoForwardBranchesNone,
 	sync.FetchAndAutoForwardBranchesOnlyMainBranches,
 	sync.FetchPrune,