Invalidate less-node file cache if modified (#3219)

lib/less-node/file-manager.js

@@ -108,18 +108,32 @@ FileManager.prototype.loadFile = function(filename, currentDirectory, options, e
  }
  }
 
+ var modified = false;
+
  if (self.contents[fullFilename]) {
- fulfill({ contents: self.contents[fullFilename], filename: fullFilename});
+ try {
+ var stat = fs.statSync.apply(this, [fullFilename]);
+ if (stat.mtime.getTime() === self.contents[fullFilename].mtime.getTime()) {
+ fulfill({ contents: self.contents[fullFilename].data, filename: fullFilename});
+ }
+ else {
+ modified = true;
+ }
+ }
+ catch (e) {
+ modified = true;
+ }
  }
- else {
+ if (modified || !self.contents[fullFilename]) {
  var readFileArgs = [fullFilename];
  if (!options.rawBuffer) {
  readFileArgs.push('utf-8');
  }
  if (options.syncImport) {
  try {
  var data = fs.readFileSync.apply(this, readFileArgs);
- self.contents[fullFilename] = data;
+ var stat = fs.statSync.apply(this, [fullFilename]);
+ self.contents[fullFilename] = { data: data, mtime: stat.mtime };
  fulfill({ contents: data, filename: fullFilename});
  }
  catch (e) {
@@ -133,7 +147,8 @@ FileManager.prototype.loadFile = function(filename, currentDirectory, options, e
  filenamesTried.push(isNodeModule ? npmPrefix + fullFilename : fullFilename);
  return tryPrefix(j + 1);
  }
- self.contents[fullFilename] = data;
+ var stat = fs.statSync.apply(this, [fullFilename]);
+ self.contents[fullFilename] = { data: data, mtime: stat.mtime }; 
  fulfill({ contents: data, filename: fullFilename});
  });
  fs.readFile.apply(this, readFileArgs);