Don't reset error codes on CI build (#11655)

* Don't reset error codes on CI build

* Add an explanation

scripts/circleci/build.sh

@@ -3,7 +3,10 @@
 set -e		
 
 yarn build --extract-errors
-git checkout -- scripts/error-codes/codes.json
+# Note: since we run the full build including extracting error codes,
+# it is important that we *don't* reset the change to `scripts/error-codes/codes.json`.
+# When production bundle tests run later, it needs to be available.
+# See https://github.com/facebook/react/pull/11655.
 
 # Do a sanity check on bundles
 node ./scripts/rollup/validate/index