[Sqlalchemy-tickets] Issue #4219: autoload existing mysql table throws Unknown schema content (zzzeek/sqlalchemy)

[LiQuan <iss...@bi...>]

New issue 4219: autoload existing mysql table throws Unknown schema content
https://bitbucket.org/zzzeek/sqlalchemy/issues/4219/autoload-existing-mysql-table-throws

LiQuan:

My existing table created with following sql
```
CREATE TABLE `fx_orders_items` (
  .....
  FULLTEXT KEY `ix_fulltext_oi_g_name` (`oi_g_name`) /*!50100 WITH PARSER `ngram` */ 
) ENGINE=InnoDB AUTO_INCREMENT=100018857 DEFAULT CHARSET=utf8 COMMENT=''
```
when I use autoload like this
```
Table("fx_orders_items", metadata, autoload=True)
```

it throws error
```
C:\Python27\lib\site-packages\sqlalchemy\dialects\mysql\reflection.py:57: SAWarning: Unknown schema content: u'  FULLTEXT KEY `ix_fulltext_oi_g_name` (`oi_g_name`) /*!50100 WITH PARSER `ngram` */ '
  util.warn("Unknown schema content: %r" % line)
```

I just debug it and found the line 
```
FULLTEXT KEY `ix_fulltext_oi_g_name` (`oi_g_name`) /*!50100 WITH PARSER `ngram` */ 
```
didn't go into any of this and return None
```
def _parse_constraints(self, line):
        """Parse a KEY or CONSTRAINT line.

        :param line: A line of SHOW CREATE TABLE output
        """
        m = self._re_key.match(line)
        m = self._re_fk_constraint.match(line)
        m = self._re_ck_constraint.match(line)
        m = self._re_partition.match(line)

        # No match.
        return (None, line)
```