Nobody panic :).

r31548 of trunk is not Twisted 11.0.0.  Twisted 11.0 diverged from trunk as of <http://twistedmatrix.com/trac/changeset/31390>.

Perhaps more tellingly, there is no _newtls.py in Twisted 11.0: <http://twistedmatrix.com/trac/browser/tags/releases/twisted-11.0.0/twisted/internet>.  (Plus, I triple-checked the tarballs just now to make sure that they were released from the right place, and they were.)

That revision of trunk would include <http://twistedmatrix.com/trac/changeset/31537> though, which is some new SSL code _not_ included in the 11.0 release.

So - yes, this is a bug, but NOT in the 11.0 release.

Please file a bug, noting that it's a regression.  Depending on what level of nastiness foolscap is getting up to in order to trigger this behavior, we may have to revert <http://tm.tl/4854>.