[neutron] Please hold off on merging patches

Hi Neutrinos, It was noticed today by Mohammed Naser that the neutron gate was only running the docs and pep8 jobs. We were able to track it down to the RE2 patches that were recently merged [0]. Until the reverts land please don't +W anything since it could merge untested and would just need to be reverted. Other projects might have similar issues if they updated code using the 'negate' directive for regex recently as we found it doesn't actually work with RE2 when using negative lookahead [1]. Thanks, -Brian [0] https://review.opendev.org/q/topic:"files-negate" [1] https://github.com/google/re2/issues/156