Release GIL while waiting on schedd response. #4507
Make locking more fine-grained in the htcondor module. #4507

Prior to this commit, any queries into the HTCondor python module
would block the entire python process, including all other threads.
With this work, we release the GIL around communication with the
remote server and acquire a module-level lock.  Only one HTCondor
thread can progress at a time - but the rest of the python
application can do things in other modules.
Disable classad caching when the HTCondor module loads. #4507