twisted.web.static.FileTransfer pointlessly uses threadable.synchronized

[exarkun]

FileTransfer should not bother to pretend to provide a threadsafe API. Synchronizing resumeProducing doesn't actually make it threadsafe to call self.request.write from another thread.

[exarkun]

(In [23910]) Branching to 'unsynchronized-2985'

[exarkun]

Removed, and did some other minor cleanups.

[therve]

Looks cool. There is a bunch of other cleanups which would be nice to make:

• remove string import
• remove future import
• remove trailing whitespaces

Nothing mandatory though, so merge when you want.

[exarkun]

(In [23946]) Merge unsynchronized-2985

Author: exarkun Reviewer: therve Fixes: #2985

Remove the code which synchronizes methods of FileTransfer. The methods aren't threadsafe even if they're guaranteed to be serialized.

Also make some minor cleanups to nearby code, removing trailing whitespace and no-longer needed imports.