vendors/tempy.js/makeAbs
    function makeAbs(self, f) {
      var abs = f;
      if (f.charAt(0) === "/") {
        abs = path2.join(self.root, f);
      } else if (isAbsolute(f) || f === "") {
        abs = f;
      } else if (self.changedCwd) {
        abs = path2.resolve(self.cwd, f);
      } else {
        abs = path2.resolve(f);
      }
      if (process.platform === "win32")
        abs = abs.replace(/\\/g, "/");
      return abs;
    }