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

* Don't reset error codes on CI build

* Add an explanation

Author: gaearon

scripts/circleci/build.sh

@@ -4,6 +4,11 @@ set -e
 
 yarn build --extract-errors
 
+# 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