fix: ensure directories are watched, not files

Fixes #1259

lib/monitor/watch.js

@@ -7,6 +7,7 @@ var chokidar = require('chokidar');
 var undefsafe = require('undefsafe');
 var config = require('../config');
 var path = require('path');
+const fs = require('fs');
 var utils = require('../utils');
 var bus = utils.bus;
 var match = require('./match');
@@ -48,6 +49,12 @@ function watch() {
         ignored.push(dotFilePattern);
       }
 
+      // if the directory is a file, it somehow causes
+      // windows to lose the filename upon change
+      if (fs.statSync(dir).isFile()) {
+        dir = path.dirname(dir);
+      }
+
       var watchOptions = {
         ignorePermissionErrors: true,
         cwd: dir,