When will JDK 9 builds move to requiring the boot JDK be JDK 8?

[Alan Bateman]

We had problems in jdk9/dev in the last day or so where there were 
changes pushed to the corba repo that use APIs that are new in JDK 8. 
This caused problems when building jdk9/dev with a 7uX build as the boot 
JDK and made it obvious that there are a mix of boot JDKs in use (some 
people use 7uX, some use 8).

I'm wondering when is the time to move to requiring the boot JDK be a 
JDK 8 build? This came up in December too when a change to langtools had 
to be reserved in order to keep jdk9/dev building with a 7uX build as 
the boot JDK.

Are there any reasons not to switch now?

-Alan.