Bootstrap javac having problem finding features flags

From Jim Laskey:

Ran into a javac bootstrap issue not sure what is wrong. I switched from a 13 to a 14 bootstrap for my text blocks changes and now I'm getting.

warning: unknown enum constant Feature.TEXT_BLOCKS
warning: unknown enum constant Feature.TEXT_BLOCKS
warning: unknown enum constant Feature.TEXT_BLOCKS

for the 3 checkSourceLevel in JavaTokenizer.java.

but Source clearly has TEXT_BLOCKS(JDK15, Fragments.FeatureTextBlocks, DiagKind.PLURAL),

JavaTokenizer.java has import com.sun.tools.javac.code.Source.Feature;

This is after a nuked build folder configure

Switching back to 13 works fine