[PATCH] Make mysql adapter keep non-standard primary key names in SchemaDumper.dump

I just discovered that the patch won't apply to the current edge due to changes to use migrations to populate the test db.

I've attached a new patch which works with the current edge.

+1

(In [8012]) Make sure that the Schema Dumper supports non-standard primary keys with MySQL. Closes #9971 [RubyRedRick]

I believe line 445 of the applied patch is superfluous, since line 447 also executes the "describe #{table}" command.

443           # Returns a table's primary key and belonging sequence. 
444           def pk_and_sequence_for(table) #:nodoc: 
445             table_desc_result = execute("describe #{table}") 
446             keys = [] 
447             execute("describe #{table}").each_hash do |h| 
448               keys << h["Field"]if h["Key"] == "PRI" 
449             end 
450             keys.length == 1 ? [keys.first, nil] : nil 
451           end 

(In [8015]) Remove superfluous code and quote table name. References #9971 [jkit, nzkoz]