Starting a script with large file upload "hangs"

[bugy]

When you try to start a script with a large upload (more than supported by the server), interface hangs:

• Log says "calling the script"
• Stop/execute button are disabled
• In the browser console there are errors
• In the server logs there is an error:
  [tornado.general.INFO] Malformed HTTP message from 127.0.0.1: Content-Length too long

[bugy]

The server and client errors are expected (because the file is indeed larger, than allowed on the server). However in this case the error should be shown to a user, instead of handing the interface.

[bugy]

Apparently this issue is reproducible only on Windows. But it could probably also happen on linux for some weird connection problems.