Workaround for breaking upstream change

Closes ef4#20

lib/caching-browserify.js

@@ -106,7 +106,24 @@ module.exports = CoreObject.extend({
     b.add('./' + self.inFile);
 
     b.on('package', function(pkg){
-      self._watchModules[pkg.__dirname] = true;
+      // browserify *used to* reliably put the package's directory in
+      // pkg.__dirname. But as of browser-resolve 1.7.0 that isn't
+      // true, and we sometimes get a value here like
+      // '/path/to/your-module/index' instead of
+      // '/path/to/your-module'. So we do our own checking.
+      var pkgDir = pkg.__dirname;
+      var stat;
+      try {
+        stat = fs.statSync(pkgDir);
+      } catch(err) {
+        if (err.code !== 'ENOENT') {
+          throw err;
+        }
+      }
+      if (!stat || !stat.isDirectory()) {
+        pkgDir = path.dirname(pkgDir);
+      }
+      self._watchModules[pkgDir] = true;
     });
 
     b.on('dep', function (dep) {