Creating a sender for a non-existent queue blocks any further creating of a similarly named sender.

If I create a sender using:

sender = session.create_sender("my-queue")

and no such queue exists, then later doing:

sender = session.create_sender("my-queue;

")

fails with:

SessionError: not-found: not-found: Queue not found: my-queue (/builddir/build/BUILD/qpid-0.24/cpp/src/qpid/broker/SessionAdapter.cpp:690)