Install 'winston' 0.6.2, require it, then clean all module cache, install 'winston' 0.7.2 and require it. It will fail because 'winston' 0.6.x uses 'async' 0.1 whereas 'winston' 0.7.x uses 'async' 0.2, which has changed its main file. Since the main file name is kept in cache in the variable packageMainCache (in module.js), the module will not b…

node_cache_test.js

var npm = require('npm');

npm.load({}, function (er) {
  if (er) console.log(er)
  npm.commands.install(["winston@0.6.2"], function (er, data) {
    if (er) {
      console.log("npm install failed: " + er);
    }
    else {
      var winston = require('winston');
      console.log("Winston version: " + winston.version);
      upgradeWinstonVersion();
    }
  });
  npm.on("log", function (message) { console.log(message) });
});


function cleanModuleCache(moduleName) {
  var mod = require.resolve(moduleName);
  if (mod && ((mod = require.cache[mod]) !== undefined)) {
    (function run(mod) {
      mod.children.forEach(function (child) {
        run(child);
      });
      delete require.cache[mod.id];
    })(mod);
  }

  Object.keys(module.constructor._pathCache).forEach(function(cacheKey) {
    if (cacheKey.indexOf(moduleName) > 0) {
      delete module.constructor._pathCache[cacheKey];
    }
  });
};

function upgradeWinstonVersion() {
  cleanModuleCache('winston');

  npm.commands.install(["winston@0.7.2"], function (er, data) {
    if (er) {
      console.log("npm install failed: " + er);
    }
    else {
      var winston = require('winston');
      console.log("Winston version: " + winston.version);
    }
  });
}

Here's an extremely ugly workaround, but it works, till #8266 get reopened, discussed and hopefully resolved.

Override the Module._findPath function, along with all the helper functions that it depends on, I tested this and it works. Good luck.

https://gist.github.com/akhoury/85a4a84ed244c9c2053a

It works indeed! But I think will look at other possibilities for what I wanted to achieve, and I will see if the issue get reopened. Thanks for your investigation!