Do not generate *test.js.flow files.

Author: StevenXL

dist/use-extra-deps/index.test.js.flow

@@ -9,7 +9,7 @@
     "test": "jest",
     "test:watch": "yarn run test -- --watch",
     "check-git-clean": "./check-git-clean.sh",
-    "gen-flow": "yarn run flow-copy-source --ignore \"*.test.js\" src dist"
+    "gen-flow": "yarn run flow-copy-source --ignore '**/*.test.js' src dist"
   },
   "babel": {
     "presets": [