Try to fix cosmiconfig in the built version of Prettier (#2930)

scripts/build/rollup.bin.config.js

@@ -11,7 +11,14 @@ export default Object.assign(baseConfig, {
   banner: "#!/usr/bin/env node",
   plugins: [
     replace({
-      "#!/usr/bin/env node": ""
+      "#!/usr/bin/env node": "",
+      // The require-from-string module (a dependency of cosmiconfig) assumes
+      // that `module.parent` exists, but it only does for `require`:ed modules.
+      // Usually, require-from-string is _always_ `require`:ed, but when bundled
+      // with rollup the module is turned into a plain function located directly
+      // in bin/prettier.js so `module.parent` does not exist. Defaulting to
+      // `module` instead seems to work.
+      "module.parent": "(module.parent || module)"
     }),
     json(),
     resolve({ preferBuiltins: true }),

scripts/build/rollup.index.config.js

@@ -2,11 +2,25 @@ import baseConfig from "./rollup.base.config.js";
 import resolve from "rollup-plugin-node-resolve";
 import commonjs from "rollup-plugin-commonjs";
 import json from "rollup-plugin-json";
+import replace from "rollup-plugin-replace";
 
 export default Object.assign(baseConfig, {
   entry: "index.js",
   dest: "dist/index.js",
   format: "cjs",
-  plugins: [json(), resolve({ preferBuiltins: true }), commonjs()],
+  plugins: [
+    replace({
+      // The require-from-string module (a dependency of cosmiconfig) assumes
+      // that `module.parent` exists, but it only does for `require`:ed modules.
+      // Usually, require-from-string is _always_ `require`:ed, but when bundled
+      // with rollup the module is turned into a plain function located directly
+      // in index.js so `module.parent` does not exist. Defaulting to `module`
+      // instead seems to work.
+      "module.parent": "(module.parent || module)"
+    }),
+    json(),
+    resolve({ preferBuiltins: true }),
+    commonjs()
+  ],
   external: ["assert"]
 });