Fix incorrect PostgreSQL connection string for Unix sockets (#28865)

Fix #28864

modules/setting/database.go

@@ -169,8 +169,8 @@ func getPostgreSQLConnectionString(dbHost, dbUser, dbPasswd, dbName, dbsslMode s
 		RawQuery: dbParam,
 	}
 	query := connURL.Query()
-	if strings.HasPrefix(dbHost, "/") { // looks like a unix socket
-		query.Add("host", dbHost)
+	if strings.HasPrefix(host, "/") { // looks like a unix socket
+		query.Add("host", host)
 		connURL.Host = ":" + port
 	}
 	query.Set("sslmode", dbsslMode)

modules/setting/database_test.go

@@ -77,6 +77,14 @@ func Test_getPostgreSQLConnectionString(t *testing.T) {
 			SSLMode: "false",
 			Output:  "postgres://testuser:space%20space%20%21%23$%25%5E%5E%25%5E%60%60%60-=%3F=@:5432/gitea?host=%2Ftmp%2Fpg.sock&sslmode=false",
 		},
+		{
+			Host:    "/tmp/pg.sock:6432",
+			User:    "testuser",
+			Passwd:  "pass",
+			Name:    "gitea",
+			SSLMode: "false",
+			Output:  "postgres://testuser:pass@:6432/gitea?host=%2Ftmp%2Fpg.sock&sslmode=false",
+		},
 		{
 			Host:    "localhost",
 			User:    "pgsqlusername",