Fix `IsObjectExist` with gogit (#31790) (tests only)

Fix #31271.

When gogit is enabled, `IsObjectExist` calls
`repo.gogitRepo.ResolveRevision`, which is not correct. It's for
checking references not objects, it could work with commit hash since
it's both a valid reference and a commit object, but it doesn't work
with blob objects.

So it causes #31271 because it reports that all blob objects do not
exist.

(cherry picked from commit f4d3120f9d1de6a260a5e625b3ffa6b35a069e9b)

Conflicts:
  trivial resolution because go-git support was dropped https://codeberg.org/forgejo/forgejo/pulls/4941

modules/git/repo_branch_test.go

@@ -95,3 +95,103 @@ func BenchmarkGetRefsBySha(b *testing.B) {
 	_, _ = bareRepo5.GetRefsBySha("c83380d7056593c51a699d12b9c00627bd5743e9", "")
 	_, _ = bareRepo5.GetRefsBySha("58a4bcc53ac13e7ff76127e0fb518b5262bf09af", "")
 }
+
+func TestRepository_IsObjectExist(t *testing.T) {
+	repo, err := openRepositoryWithDefaultContext(filepath.Join(testReposDir, "repo1_bare"))
+	require.NoError(t, err)
+	defer repo.Close()
+
+	supportShortHash := true
+
+	tests := []struct {
+		name string
+		arg  string
+		want bool
+	}{
+		{
+			name: "empty",
+			arg:  "",
+			want: false,
+		},
+		{
+			name: "branch",
+			arg:  "master",
+			want: false,
+		},
+		{
+			name: "commit hash",
+			arg:  "ce064814f4a0d337b333e646ece456cd39fab612",
+			want: true,
+		},
+		{
+			name: "short commit hash",
+			arg:  "ce06481",
+			want: supportShortHash,
+		},
+		{
+			name: "blob hash",
+			arg:  "153f451b9ee7fa1da317ab17a127e9fd9d384310",
+			want: true,
+		},
+		{
+			name: "short blob hash",
+			arg:  "153f451",
+			want: supportShortHash,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, repo.IsObjectExist(tt.arg))
+		})
+	}
+}
+
+func TestRepository_IsReferenceExist(t *testing.T) {
+	repo, err := openRepositoryWithDefaultContext(filepath.Join(testReposDir, "repo1_bare"))
+	require.NoError(t, err)
+	defer repo.Close()
+
+	supportBlobHash := true
+
+	tests := []struct {
+		name string
+		arg  string
+		want bool
+	}{
+		{
+			name: "empty",
+			arg:  "",
+			want: false,
+		},
+		{
+			name: "branch",
+			arg:  "master",
+			want: true,
+		},
+		{
+			name: "commit hash",
+			arg:  "ce064814f4a0d337b333e646ece456cd39fab612",
+			want: true,
+		},
+		{
+			name: "short commit hash",
+			arg:  "ce06481",
+			want: true,
+		},
+		{
+			name: "blob hash",
+			arg:  "153f451b9ee7fa1da317ab17a127e9fd9d384310",
+			want: supportBlobHash,
+		},
+		{
+			name: "short blob hash",
+			arg:  "153f451",
+			want: supportBlobHash,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, repo.IsReferenceExist(tt.arg))
+		})
+	}
+}

modules/markup/html.go

@@ -1197,7 +1197,7 @@ func hashCurrentPatternProcessor(ctx *RenderContext, node *html.Node) {
 				})
 			}
 
-			exist = ctx.GitRepo.IsObjectExist(hash)
+			exist = ctx.GitRepo.IsReferenceExist(hash)
 			ctx.ShaExistCache[hash] = exist
 		}