Description:
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When maintaining two connections to the same mysql server mysql_select_db requests with the connection id supplied are setting both connections to use that database. 

Reproduce code:
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$silver = mysql_connect('localhost','user','pass', true);
mysql_select_db('silver',$silver);
$lemon = mysql_connect('localhost','user','pass', true);
mysql_select_db('lemon',$lemon);
$silver_result = mysql_query('select * from errors') or print("The query has become invalid: \"".mysql_errno().": ".mysql_error()."\"");

var_dump($silver);
var_dump($lemon);

Expected result:
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query should execute on silver.errors

Actual result:
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I get an error that lemon.errors does not exist, even though both $silver and $lemon have different connection ids...