Visualize local branch heads in commits panel

We want to mark all local branch heads with a "*" in the local commits panel, to
make it easier to see how branches are stacked onto each other. In order to not
confuse users with "*" markers that they don't understand, do this only for the
case where users actually use stacked branches; those users are likely not going
to be confused by the display. This means we want to filter out a few branch
heads that shouldn't get the marker: the current branch, any main branch, and
any old branch that has been merged to master already.

pkg/gui/presentation/commits_test.go

@@ -28,6 +28,8 @@ func TestGetCommitListDisplayStrings(t *testing.T) {
 	scenarios := []struct {
 		testName                 string
 		commits                  []*models.Commit
+		branches                 []*models.Branch
+		currentBranchName        string
 		fullDescription          bool
 		cherryPickedCommitShaSet *set.Set[string]
 		diffName                 string
@@ -72,6 +74,73 @@ func TestGetCommitListDisplayStrings(t *testing.T) {
 		sha2 commit2
 						`),
 		},
+		{
+			testName: "commit with tags",
+			commits: []*models.Commit{
+				{Name: "commit1", Sha: "sha1", Tags: []string{"tag1", "tag2"}},
+				{Name: "commit2", Sha: "sha2"},
+			},
+			startIdx:                 0,
+			length:                   2,
+			showGraph:                false,
+			bisectInfo:               git_commands.NewNullBisectInfo(),
+			cherryPickedCommitShaSet: set.New[string](),
+			now:                      time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC),
+			expected: formatExpected(`
+		sha1 tag1 tag2 commit1
+		sha2 commit2
+						`),
+		},
+		{
+			testName: "show local branch head, except the current branch, main branches, or merged branches",
+			commits: []*models.Commit{
+				{Name: "commit1", Sha: "sha1"},
+				{Name: "commit2", Sha: "sha2"},
+				{Name: "commit3", Sha: "sha3"},
+				{Name: "commit4", Sha: "sha4", Status: models.StatusMerged},
+			},
+			branches: []*models.Branch{
+				{Name: "current-branch", CommitHash: "sha1", Head: true},
+				{Name: "other-branch", CommitHash: "sha2", Head: false},
+				{Name: "master", CommitHash: "sha3", Head: false},
+				{Name: "old-branch", CommitHash: "sha4", Head: false},
+			},
+			currentBranchName:        "current-branch",
+			startIdx:                 0,
+			length:                   4,
+			showGraph:                false,
+			bisectInfo:               git_commands.NewNullBisectInfo(),
+			cherryPickedCommitShaSet: set.New[string](),
+			now:                      time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC),
+			expected: formatExpected(`
+		sha1 commit1
+		sha2 * commit2
+		sha3 commit3
+		sha4 commit4
+						`),
+		},
+		{
+			testName: "show local branch head and tag if both exist",
+			commits: []*models.Commit{
+				{Name: "commit1", Sha: "sha1"},
+				{Name: "commit2", Sha: "sha2", Tags: []string{"some-tag"}},
+				{Name: "commit3", Sha: "sha3"},
+			},
+			branches: []*models.Branch{
+				{Name: "some-branch", CommitHash: "sha2"},
+			},
+			startIdx:                 0,
+			length:                   3,
+			showGraph:                false,
+			bisectInfo:               git_commands.NewNullBisectInfo(),
+			cherryPickedCommitShaSet: set.New[string](),
+			now:                      time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC),
+			expected: formatExpected(`
+		sha1 commit1
+		sha2 * some-tag commit2
+		sha3 commit3
+						`),
+		},
 		{
 			testName: "showing graph",
 			commits: []*models.Commit{
@@ -285,6 +354,8 @@ func TestGetCommitListDisplayStrings(t *testing.T) {
 				result := GetCommitListDisplayStrings(
 					common,
 					s.commits,
+					s.branches,
+					s.currentBranchName,
 					s.fullDescription,
 					s.cherryPickedCommitShaSet,
 					s.diffName,