file locking not possible over smb mounts

[cvandeplas]

on MacOS X and with data on a network share:

(venv) chri@Christophes-iMac sysdiagnose % ./sysdiagnose.py -c public parse logarchive
Traceback (most recent call last):
  File "/Volumes/VMware Shared Folders/sysdiagnose/sysdiagnose/./sysdiagnose.py", line 191, in cases
    fcntl.flock(f, fcntl.LOCK_EX)        # enable lock
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [Errno 45] Operation not supported

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Volumes/VMware Shared Folders/sysdiagnose/sysdiagnose/./sysdiagnose.py", line 482, in <module>
    main()
  File "/Volumes/VMware Shared Folders/sysdiagnose/sysdiagnose/./sysdiagnose.py", line 110, in main
    elif not sd.is_valid_case_id(args.case_id):
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Volumes/VMware Shared Folders/sysdiagnose/sysdiagnose/./sysdiagnose.py", line 392, in is_valid_case_id
    return case_id in self.cases()
                      ^^^^^^^^^^^^
  File "/Volumes/VMware Shared Folders/sysdiagnose/sysdiagnose/./sysdiagnose.py", line 204, in cases
    fcntl.flock(f, fcntl.LOCK_UN)
OSError: [Errno 45] Operation not supported