Our vendored copy of typeshed is very old and should get updated. Other than general fixes and improvements, there have been some additions/tweaks to the third_party directory which would likely benefit users of libraries like flask or requests.

Additionally, our typeshed updating script should write out the git hash of what version we have so we can keep track of what is checked out.

The script could be changed to do:

1. NEW: Grab the latest master hash from the repo.
2. Download the zip archive for that hash (instead of grabbing master and then asking for the version).
3. Extract the archive.
4. NEW: Mark the directory and its contents as read-only.
5. NEW: Write the hash out to a file, like version.txt or something.