Zend Db: Multiple nested selects - Zend Paginator with nested select bind parameters error

Using 2.2.4 with mysqli.

Zend\Db\Sql\AbstractSql->processSubSelect

This method keeps track of the number of subselects and so parameter keys do not get overwritten. However when using the Zend Paginator you get a:

Warning: mysqli_stmt::bind_param(): Number of variables doesn't match number of parameters in prepared statement

The code to replicate this is at https://gist.github.com/nicklevett/7253154.

This what is produced by Zend\Db\Adapter\ParameterContainer->merge:
```
array(6) {
  'subselect1where1' =>
  string(4) "%AB%"
  'subselect1where2' =>
  int(4)
  'subselect1where3' =>
  int(1)
  'subselect1where4' =>
  int(2)
  'subselect1where5' =>
  int(1)
  'subselect1where6' =>
  bool(true)
}
```
But should be:
```
array(6) {
  'subselect1where1' =>
  int(1)
  'subselect1where2' =>
  int(4)
  'subselect1where3' =>
  int(1)
  'subselect1where4' =>
  int(2)
  'subselect1where5' =>
  int(1)
  'subselect1where6' =>
  bool(true)
  'subselect2where1' =>
  string(4) "%AB%"
}
```
The subselect is not incremented so subselect1where1 gets overwritten