Inputs occured in depGraph cycle is dangenrous and should be treated as an 
invariant since Forget _may_ generate broken code in this case, despite that 
technically this is a stricter then what we needed for the particular case of 
#633 and #634 and there   could be case that this is safe (like many `cfg-`   
tests that I have to mark as `bailout.`) 

I expect the next diff will fix them though. 

commit-id:0b13ed02