Providing Schematics to a Contract Manufacturer?
Is this common practice for CMs to ask for schematics ?


Yes, I've had a few ask about it. Do I send them, No. They don't need them. Usually the problem is over a repair, or a question about a section of the design. I ask them what designators they need to look at and if they really need it, I send them a subsection of the schematic. 


  Is it common practice to bundle schematics with a fabrication+assembly
  package ?


Don't send out your IP (intellectual property) to contract manufactures, it's not good business or engineering practice. 

The contract manufacturer can get what they want through good communication without the risk of compromising IP.  

If the contract manufacturer were redesigning a schematic, yes you would need to send them the schematic.