Ensure the the config file isn't re-processed when users load a partial config and then pass it back to Babel.

packages/babel-core/src/config/partial.js

@@ -49,6 +49,7 @@ export default function loadPrivatePartialConfig(
   // passed back to Babel a second time, it will be in the right structure
   // to not change behavior.
   options.babelrc = false;
+  options.configFile = false;
   options.envName = envName;
   options.cwd = absoluteCwd;
   options.passPerPreset = false;

packages/babel-core/test/config-chain.js

@@ -904,6 +904,7 @@ describe("buildConfigChain", function() {
   describe("config files", () => {
     const getDefaults = () => ({
       babelrc: false,
+      configFile: false,
       cwd: process.cwd(),
       envName: "development",
       passPerPreset: false,