`select parseDateTimeBestEffort('01/12/2017, 18:31:44')`

It is confused by a comma - should be easy to fix.
#include <Common/DateLUTImpl.h>
#include <Common/StringUtils/StringUtils.h>
#include <IO/ReadBuffer.h>
#include <IO/ReadHelpers.h>
#include <IO/WriteHelpers.h>
#include <IO/parseDateTimeBestEffort.h>
#include <limits>
namespace DB
{
namespace ErrorCodes
{
    extern const int LOGICAL_ERROR;
    extern const int CANNOT_PARSE_DATETIME;
}
namespace
{
inline size_t readDigits(char * res, size_t max_chars, ReadBuffer & in)