generated_not_to_break_here breaks coco

[e]

The Nim compiler is putting lines like this into the generated C code: 
    
    
    #line 999999 "generated_not_to_break_here"
    
    
    Run

This is breaking `coco`, which uses `lcov` by causing it to try to process the 
file `generated_not_to_break_here`, which doesn't exist.

Is there a workaround?