DataSourceTransactionManager resets ConnectionHolder on doBegin failure

Issue: SPR-12280

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/DataSourceTransactionManager.java

@@ -238,7 +238,10 @@ public class DataSourceTransactionManager extends AbstractPlatformTransactionMan
 		}
 
 		catch (Throwable ex) {
+			if (txObject.isNewConnectionHolder()) {
 				DataSourceUtils.releaseConnection(con, this.dataSource);
+				txObject.setConnectionHolder(null, false);
+			}
 			throw new CannotCreateTransactionException("Could not open JDBC Connection for transaction", ex);
 		}
 	}